Dultmeier Sales stocks valves of all different makes, models, and applications. Here you will find all you need to know about the different types of valves we stock and the various applications they are used for. More importantly, we will help you determine what you need to know prior to making a valve purchase. Let's dig in...
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What is a valve? What are some common trade names, associated with, the valves that Dultmeier Sales stocks and distributes? In a nutshell, a valve is a product which is used to constrict, cut off, redirect, or regulate the flow of a liquid or gas. While we do sell pneumatic valves we will be primarily focusing liquid, or solution, valves for this educational segment. Some common trade names associated with the valves we stock are as follows: butterfly, ball, gate, globe, angle, needle, solenoid, check, regulating, diverter, foot, relief, unloader, backflow prevention, and float valves.
As with any product, it's crucial to identify the type of valve, the manufacturer, inlet/outlet size, operating and maximum pressures, solution temperature, and the solution passing through the valve. It's critical to know what solution is passing through the valve to ensure proper chemical compatibility. Knowing the solution's PH level can also be another important factor when determining suitable components and materials.
We size valves similar to how we size pipe. Always measure the inside diameter of the inlet/outlet port. This will identify the size of the valve in question. A common mistake is that people measure the outside diameter of the inlet/outlet ports of a valve. There is one exception to this rule - if working with tubing - measure the outside diameter of the tubing. For hose and pipe, only pay attention to the inside diameter measurement.
If flow rate is important, the coefficient of volume (Cv) of various valves can be compared. Now, I understand that sounds rather technical. However, in layman's terms all that means is the higher the Cv for a valve, the more flow rate will pass thru it with the same pressure loss. In the majority of applications, this will be a non-factor but it is still important terminology to be aware of in the vast world of valves.
Most manufacturers will have a metal tag on their valve bodies to identify their brand. That manufacturer tag will identify the brand of the valve, the model, and serial number. This is an important first step in identifying what product you currently have. That being said, let's begin with a look at butterfly valves.
Here at Dultmeier Sales, we stock a variety of butterfly valves. In the butterfly valve world, it's important to first determine which style of butterfly valve you possess. The two most common styles are Wafer or Lug bodies. A wafer-style butterfly valve has "thru" bolt holes that run along through the outside rim of both pipe flanges. In contrast, a lug-style butterfly valve has threaded bolt holes on both sides of the valve body to allow for "end of line" applications. Lug-style butterfly valves are, generally, less common than wafer-style butterfly valves. Below, you will see a wafer-style valve on the left and a lug style valve on the right:
Next, we get into the topic of valve actuation. We primarily stock butterfly valves that are manually (seen above with handle) or pneumatically actuated with either double acting or spring return actuators. A double acting butterfly valve actuator requires air pressure to open the valve and then air pressure to close the valve.
A spring return butterfly actuator is used in fail-safe applications. If there is a loss of air pressure the valve will automatically close (or open) - due to the spring tension of the actuator. Spring return actuators are used in many production plants that require system flow to cease once power is cut or lost - as mentioned above, this is a fail-safe application example.
Electric Actuators are also used in many industries. While we don't stock electric actuators for butterfly valves - we have access to them. Actuators can also be provided with "positioners", limit switches and other controls.
We stock Butterfly Valves and Air Actuators from Keystone and Pratt.
A ball valve is probably the most common type of valve that exists - across all industries. It gets its name due to the fact that it actually has an internal ball that sits in a "seat". When the handle or knob is turned 90 degrees from the inlet/outlet ports, the valve is closed and one can see the convex shape of the internal ball. When the handle is turned parallel with the inlet/outlet ports, the valve is open and one can view through it - unhindered.
On the left, below, is an example of an air actuated, stainless steel, female pipe thread, ball valve. While on the right, you will see a Banjo, polypropylene, manual, flanged, ball valve.
By design, ball valves that are listed as Standard Port actually have less fluid path than the inlet/outlet ports size limitations - this is somewhat misleading to those that are unfamiliar with the concept of Standard vs. Full Port valves.
For example, if you have a 2 inch Standard Port valve your flow characteristics will be closer to that of a 1.5-inch fluid path. The technical reasoning behind this is the fact that a smaller opening creates more friction loss (i.e. pressure drop) thus resulting in a decreased flow rate. Standard port ball valves are cheaper than full port valves but restrict the system flow rates; somewhat. So, if flow rates don't matter or affect your system then you can save money up front by selecting standard port valve(s) for your plumbing system.
Full port valves allow the plumbing system to realize the full flow characteristics of the valving. If all valves in a system are two inch full port, valves then we can reasonably assume increased flow rates in comparison to a system that contains all standard port valving. A full port valve has a slight design change that allows for this increase in flow characteristics. While the valves may look the same externally, there are internal design changes that are not visible to the naked eye.
This is another crucial step in determining the correct valve for a specific application. If necessary, place a pressure gauge at various points in the plumbing system to determine the system operating pressure. Never guess the operating pressure of a system. If a low pressure valve is installed into a high pressure system, serious or fatal injury could occur. As a general rule of thumb, anything below 150 psi is considered Low Pressure - that being said, there are valves rate for pressure less than 150 psi.
This gets back to one of our core fundamentals when selecting a proper valve - determine operating pressure and maximum pressure for the intended plumbing system.
Ball valves are a perfect example of how the same style valve can be used in multiple applications - both high pressure and low pressure. We have some ball valve product lines that have use applications which are limited to certain industries - due to their operating/working pressure limitations. However, we have many ball valve lines that carry over into multiple industry applications.
While we do carry many products that can be cross-utilized in various industries we always want the customer to confirm an operating pressure. This ensures safety in application and use. Furthermore, it minimizes the possibility of injury and lessens the chance of damage to the valve and other plumbing system components
We carry ball valves that can be remotely operated via automation, as well. The most common types are pneumatic (air-operated) and electric motor-operated ball valves. Air operated are most widely used in chemical facilities, fertilizer plants, or industrial plants. Electric ball valves are most commonly used in agricultural applications for spraying applications. The trade name electric ball valve or pneumatic ball valve simply refers to how the valve is actuated.
When you drive down the road and see a large self-propelled sprayer, spraying in a field, you can be certain the booms are being remotely controlled. The boom valves are remotely controlled from the sprayer cab, with the help of electric ball valves. The sprayer operator sends a signal from his, in-cab, boom controller to turn certain sections of the sprayer boom on/off - based upon the field's specific application requirements.
We also see electric ball valves in the turf industry. Golf courses or residential sprayers will commonly use this type of ball valve on their sprayer setups. It is more prevalent in the turf industry due to the fact that the booms are much smaller than the agricultural industry.
Lastly, we do a fair amount of business in the liquid deicing industry. If you have ever seen a department of roads/transportation vehicle that is applying liquid before a winter storm - you have witnessed this industry in action. These vehicles are applying a solution called liquid salt brine (sodium chloride, magnesium or calcium chloride solution). Electric driven ball valves are common in this industry because pneumatic valve airlines would freeze in the frigid winter temperatures.
For those interested, here is a link that further explains the process of creating the salt brine solution. Below is a picture of a pneumatic-operated ball valve, on the left. On the right you will see an electric-operated ball valve.
A flanged gate valve is used in larger flow applications. In the Dultmeier world, we most commonly see this style of valve used on large bulk fertilizer, fuel tank storage applications, and float storage tanks in the vehicle and fleet washing industry. Gate Valves are generally designed with a circular handle that is turned clockwise to close the valve and counter-clockwise to open the valve.
Just as any other valve, we need to confirm the solution that will be passing through the valve to ensure chemical compatibility and then confirm the working or operating pressures that are required by the plumbing system. Most commonly, we are supplying flanged gate valves for lower pressure ranges. Below is a picture of a common flanged gate valve used in the bulk fertilizer industry.
A globe valve is very similar, from an external view, to that of a gate valve. However, when we look at the valves internally, they are quite different. As can be seen from the previous section, the gate valve operates almost like a wedge or slate that constricts or completely closes off flow. A globe valve has a different seat structure and more of a plunger that constricts or completely closes off flow. See below:
Below is a photo of a couple different sized globe valves on an Anhydrous Ammonia application. These valves are for a receiving bulkhead system where a plant facility will offload large bulk transports into their bulk storage tanks. The larger valve is on the liquid line transfer and the smaller valve is on the vapor transfer line.
In the Dultmeier Sales world, we most commonly use globe valves in the Anhydrous Ammonia industry. That is the same for angle valves. The most common application we see angle valves used in would be on toolbars or supply risers for Anhydrous Ammonia fertilizer applications. Continental Nh3 Products and Squibb Taylor are our two largest suppliers for these types of valves. An angle globe valve can be viewed below:
Next up we will take a look into needle valves and the various applications they can be used for. Most commonly, we see these valves used in higher pressure applications such as car/truck wash and high-pressure cleaning. Here is a grouping of various needle valves on our website, to further illustrate the variety of options. That being said, we do sell a fair amount of needle valves in the Anhydrous Ammonia industry for a bleed off application.
As always, in any application we want to confirm the solution passing through the valve, working or operating pressure range, and temperature of the solution. Below you can view a picture of a needle valve.
We carry a wide supply of solenoid valves from a number of suppliers. The most notable brands we offer are GC Valves, DEMA, KIP, Kingston and more. A solenoid valve is another example of an electric valve. However, they are drastically different than electric ball valves. That being said, solenoid valves can be controlled remotely and are used in a number of industries.
We most commonly use them in high-pressure vehicle or fleet washing applications, industrial applications, and agriculture or turf spraying applications. Some users in the agriculture industry are starting to migrate away from solenoid valves to ball valves - the primary reason being the necessity for the ruggedness of a ball valve versus over a solenoid valve. Mother Nature in combination with aggressive chemicals is an extremely harsh environment for a valve.
This is an important topic to address - especially in the realm of solenoid valves. If a valve is "normally closed" it means that the valve is closed in its uncharged state. More simply put, if there is no electrical current passing through the valve coil then then it will remain closed. If a valve is "normally open", that means the valve is open in its uncharged state.
Various applications will call for either style. Coils in these valves can be 12 volt, 24 volt, 110 volt and even 240 volt, which allows for a wide and versatile range of applications.
For example, in the vehicle washing industry, we may want to have a weep application on a spray gun. We would do this to ensure the gun doesn't freeze shut in lower temperatures. Therefore, we want ambient water to continuously run through the system or spray gun - if a loss of power occurs. So, in this instance we would want to ensure a normally open valve be installed in this type of a plumbing system.
Solenoid valves are still highly used in the car/truck wash industries due to the fact that they are generally stored in temperature-controlled environments while limiting exposure to the harshness of the natural elements.
Next up, we will look into the world of check valves. This product is used to prevent backflow of a solution in a plumbing system. For instance, a check valve would be utilized when pumping a solution up a vertical pipe and you do not want the solution to backflow, due to gravity, when the pump is turned off. A check valve is a form of backflow prevention.
Furthermore, check valves keep a plumbing system charged. By keeping the system charged we can ensure more efficient delivery of product and reduce the number of air pockets that are present in the plumbing system, which reduces pump priming time and other potential pump problems. The more efficient a plumbing system is - the less it costs to keep it running.
There are multiple types of check valves and each has its own benefits. We will briefly touch on the different types, here. First, is the most efficient type - in terms of maximizing flow characteristics. The swing check valve allows for maximum flow characteristics due to its design that reduces restrictions (i.e. a high coefficient of volume).
Regardless of the check valve style, we need to remember the cracking pressure. The cracking pressure determines the PSI at which the valve opens. Therefore, if a check valve has a cracking pressure of 2 psi it will not open until the plumbing system generates an operating fluid pressure greater than 2 psi. Below is a cross-cut section of a swing check valve:
Secondly, we have a ball check valve. This type of check valve has a preset mechanical spring that allows the valve to open based upon a pre-determined working pressure. These types of check valves are commonly used in high-pressure applications such as car and truck wash, but also within industrial and agricultural applications.
Lastly, there is a plunger style check valve. This style is pictured below:
Things to note when ordering a check valve:
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A regulating valve can technically be any valve. In this sense, if you can constrict or control the flow by manipulating the opening threshold of the valve - you have just regulated the system flow.
To that note, we are going to look at this section with this one caveat in mind - a regulating valve needs to be remotely controlled. To do this, let's first look into electric motor driven valves.
There are certain types actuators of ball valves or butterfly valves that manipulate the flow rate of the solution by opening or closing the valve stem a to a certain degree. Without getting too technical this is done in conjunction with some type of flow monitor that is able to communicate with the valve actuator through a control mechanism.
This control mechanism can be a simple rate controller in a sprayer cab or as complex as a computer dashboard in a chemical production facility. The regulating valve communicates to the flow monitor through the system controller to reach and/or maintain the desired flow rate. This controller can be a simple rate controller or a complex computer system.
Regardless of the application - in order to remotely control a regulating valve we must have a controller that sends a signal to the valve based upon the desired flow rate of the operator.
As always, any application we want to confirm the solution passing through the valve, operating pressure range, and temperature of the solution.
A diverter valve functions very similarly to a remotely controlled regulating valve. The main difference between a regulating valve and a diverter valve lies within the functionality. A diverter valve is designed only to guide product flow through a system. Therefore, the most common example of this would be a three-way ball valve.
We look at this section with the same caveat in mind - a regulating valve needs to be remotely controlled. To do this, let's first look into electric motor driven valves.
The diverter valve would be remotely controlled through a similar mechanism as a regulating valve. The main difference is that the diverter valve "diverts" flow down fluid path A versus fluid path B - based upon the desired location sent by the controller or computer.
Foot Valves are commonly used in transfer systems that require the pump to maintain it's prime. A foot valve is essentially a type of check valve. Foot valves are placed at the beginning of a suction line and are generally designed with some type of a strainer or screen to protect the plumbing system from sucking in foreign objects.
If you recall the design of the check valve, you will remember that a check valve closes when there is backflow pressure applied on the spring check. This forces the valve to close and keeps the system suction line primed, with liquid - thus increasing the overall efficiency of the plumbing system. The less time it takes to prime the pump the more efficient the plumbing system becomes. Below you can view a diagram of a plumbing system that includes a foot valve, with strainer.
Relief and unloader valves are commonly used in higher pressure situations with positive displacement pumps. These valves are used to protect system components from dead-head scenarios. A positive displacement pump will continue forcing product downstream in a plumbing system until there is a system failure such as a burst pipe, fitting, hose, etc. Thus, the term: dead head scenario. To help combat this scenario, relief and unloader valves were designed. Here is a diagram that explains a relief valve scenario
Wash Diagrams
This video will explain the difference between the two styles of valves. As always, Cat Pumps does an amazing job explaining content.
In any wash down application where an operation has a water supply line connected to a public water source then it's absolutely necessary, by regulation, to have a back flow prevention valve in place. We distribute for Watts and commonly sell these units in vehicle/fleet wash applications, industrial applications and fertilizer/chemical facility applications. A backflow prevention system products the main water supply in the scenario where a local business would have a system failure and back up chemical, fertilizer, hazardous material, etc. into the main water supply - backflow prevention systems inhibit this scenario from taking place.
Below is an example of a Watts back flow preventer
Float valves are used in a wide array of applications. Virtually anywhere you need to maintain the level of a supply tank - you can leverage the assistance of a float valve. Some common float valve product lines that we distribute and carry include BOB Valves, Jobe Valves, Hydro Systems, Kerrick Valve, Dema, Walters Control, and Suttner.
Below is a Dema liquid level proportioning control unit with a siphon breaker.
Another application that is extremely common with float valves is in the cattle industry. We sell a unit that allows the user to tie into a warm water source to keep stock tanks from freezing closed in frigid temperatures. The Ice Bull Automatic Ice Prevention System is engineered to automatically open when the stock tank water temperature falls below 42 degrees Fahrenheit.
When the Ice Bull sensor valve opens, .20 gallons per minute of warmer water bypasses the float valve and flows into the tank through the discharge hose. Then, when the water temperature rises above 42 degrees Fahrenheit, the thermo valve shuts off. The Ice Bull Sensor is pictured below:
We hope that this has been a helpful guide to valves. While not all valve types are listed in this post, you have certainly enhanced your general knowledge and should be better prepared to choose the correct valve for your desired application needs.
Don't forget to confirm in any application - the solution passing through the valve, operating pressure range, maximum pressure, and temperature of the solution and always confirm chemical compatibility.
As always, thanks for stopping by and come back soon.
The gate valve is the Most Common shut-off valve. Unlike ball valves, they are not quarter-turn devices; instead, they close and open through revolutions of the hand wheel.
Used in wastewater plants, power plants and process systems, the threaded system of the gate valves give them an advantage over the quarter turn system of the ball and butterfly valve in large applications.
Fluid through gate valves experiences only minimal pressure drop as gate valves allow total flow through its passage when fully open.
This post discusses the functions, symbols, advantages and disadvantages, types, and other essential things you need to know about the gate valve.
Gate valves can also be called sluice valves or knife valves. They are control valves that allow or restrict the flow of media completely. Gate valves use a flat gate to close off flow between pipe flanges.
A gate valve, being a full port valve, has an equal diameter to the pipe through which the fluid passes. Hence, unlike butterfly valves, gate valves minimise pressure losses in the fluid when fully open. Also, because of the equal pipe and valve diameters, gate valves allow for the movement of pigs within the pipe for cleaning and inspection operations.
While butterfly valves can be used in flow regulation and on-off services, gate valves should only be used in on-off services as blocking valves and also to allow fluid flow. They should not be used in throttling.
Because of their uncomplicated construction and capability to be used in different low-pressure applications, gate valves are one of The Most Common valves in the industry.
The gate valve symbol is composed of two triangles meeting at a point. A vertical line is inserted between the triangles, and solid horizontal lines extend from the opposite sides of the triangle.
The vertical line indicates the blocking operation of the gate valve, and the horizontal lines show that the valve has a two-way function in on-off applications.
The gate valve symbol used in piping and instrumentation diagrams (P&ID) is a modification of the valve symbol, which is the gate valve symbol without the vertical line between the triangles.
The three isometric symbols in the diagram indicate symbols for butt-welding end connections, flanged ends, and socket ends connections.
Gate valves can be classified in three different ways:
Gate valves are mostly differentiated into parallel and wedge-shaped valves. The parallel gate valves shut off flow using a flat gate between two parallel seats. The gate is shut when the pressure from the pipe is allowed to seal the disc to prevent any flow. These gate valves usually function in conditions with minimal pressures or pressure drops.
Knife gate valves are a common type of parallel gate valve. They use a sharply pointed gate to shut out fluids with suspended solids or slurries. The disc of a knife valve is wiped as it passes through the seat rings.
Source: Dombor
Slab Gate valves are also known as through-conduit valves. They are closing valves that include a bore in their construction. The slab gate is aligned to prevent turbulence in flow when it is fully open. The low turbulence results in a small pressure drop and makes the slab gate perfect for transmitting crude oil.
Wedge-shaped gate valves shut off fluid using a gate shaped like a wedge. The wedge gate rests on two seats inclined in opposite directions. In this valve, the seals are tightened by extra pressure from the wedge seats. The gates last longer due to reduced contact with the seats.
The split wedge gate design seals effectively due to its malleability. Also, In cases where the inclined seats are not aligned properly, leading to more contact with the seats, the split wedge does not jam due to its malleability. This Gate Valve Design functions effectively with abrasive fluids.
Source: Indiamart
Solid wedge gate valves are a type of gate valve with a solid structure and construction. They are very common valves because they can be used in various pipe positions.
Source: Made-in-China
Flexible wedge gate valves are available in different forms. Each of these forms offers specific advantages. For example, the narrow flexible wedge gate has a strong structure but is not very malleable, unlike the wider gate, which is more flexible. They are usually found in steam systems.
Source: Alibaba
The gate in the metal seated gate valve is shaped like a cone and enters into a hole in the bottom of the valve when it closes, supported by inclined seats. Impurities are a constant feature of the metal seated valve because of its closure design, leading to wearing out of the gate.
The metal seated gate valve was used before producing resilient seated gate valves.
Resilient seated gate valves, because of the valve’s flat base, allow impurities to pass through without being stored in a hole as in the metal seated gate valve.
The rubber element in the gate sucks in the impurities as it closes, and the impurities are cleaned off when it opens again, allowing the gate to return to its normal form.
Rising stem-designed gate valves have stems outside the valve body and move with the gate. As the gate moves upward, so does the stem and vice versa. This movement allows the stem to be monitored for maintenance. This design is best used for surface installations.
Source: Alibaba
In non-rising stem designs, the stem rotates with the gate movement from inside the valve body. An indicator on top of the stem shows the position of the valve. This design can be used in industrial gate valves for surface and underground installations.
Parallel Expanding Gate Valve
Source: Made-in-China
These valves seal by the combination of two slab gate valves. The mechanically expanding gates are sealed effectively at the gate seats. They find application mostly in electric systems and petroleum industries.
When used as a Control Valve, the gate valve can effectively function in several industrial operations. Like other industrial control valves, the gate valve has advantages and disadvantages. Some of its advantages are:
Minimal Flow Resistance
The gate valve is a full port valve. Hence it allows easy passage of fluid with minimal resistance. Unlike other valves, when fully open, the gate valve body does not affect the flow motion or direction.
Better Sealing Operation
Gate valves perform better sealing operations than the shutoff valve, which is also a control valve. Even though slower than some other valves, the gate valve offers faster opening and closing operations than the shutoff valve.
Gate Valves Have Various Applications
Gate valves can function effectively with fluids such as oil, steam, slurries, and suspended fluids. Also, they can function as low vacuum system valves or venting valves.
Bidirectional Flow
If you are looking for more details, kindly visit Stainless Steel Gate Valve Supplier.
Gate valves are not restricted to one direction of flow. They are two-way directional valves, and they do not depend on the direction of the medium. Gate valves are good for operations where the fluid direction may switch.
Other advantages of the gate valves include:
Due to the slow opening and closing operations of the gate valves, a water hammer is prevented when the valve is shut.
In gate valves, impurities are usually washed away by the flowing media.
Gate valves operate in higher pressure conditions than the butterfly valve.
They work effectively with high viscosity fluids.
For industrial Valve Manufacturers, the gate valve offers a simple and easy construction. Also, they are easy to install and replace.
Small torque is required in opening and closing the gate.
Gate Valves Operate Slowly
Gate valves can be severely damaged if they are open or closed halfway. Hence the gate has to be withdrawn fully into the upper valve area when open and must be allowed to rest on the valve seat when closed before fluid flow.
The movement from the upper valve area to the bottom takes a lot of time, leading to the slow operation of gate valves. Due to its slow operation, gate valves can not be used for fast processes.
Damage From Frequent Seat Contact
The valve gate makes contact frequently with the valve seat; this may lead to scrapings on the gate surface. Surface scrapings cause damage to the gate with time resulting in the shorter life span of gate valves. Damages on the gate surface are not easily repaired.
Other disadvantages of gate valves include:
They are larger and therefore require more space than butterfly valves.
Gate valves are usually used in on/off services where they function in allowing or restricting flow. For better efficiency, gate valves should not be used regularly, as frequent friction would lead to the shorter service life of the valve.
Because of its ability to allow flow through the pipeline with minimal pressure losses and permit easy operation of pigs for inspection and cleaning, the gate valve is a commonly used valve for blocking and isolation.
However, gate valves should not be used for flow regulation. Constant fluid contact with the gate causes damage to the disc and seat and invariably shortens the valve’s service life.
They have a wide application in the industry which includes operations in petroleum refineries, power plants, manufacturing factories, and chemical production companies. The gate valves function effectively in high temperature and pressure conditions.
Source: HardHat Engineering
The gate valve includes the body, hand wheel, yoke, bonnet, packing gland, stew, and gate. Each part will be explained below.
The valve body is responsible for housing the valve trim and allowing fluid to pass from one pipe end to another. Valve bodies are made from metals, an alloy of metals, or nonmetals of varying kinds.
Also called shells, the gate valve body can be joined to the pipe flanges by butt, sockets, wafers, or threaded ends.
The gate valve body is of three different designs, which depend on the purpose of the gate valve. The designs are Reduced Bore, Full Bore, and Cross Flow.
The bonnet of gate valves primarily functions as valve covers and support for other parts of the valve, such as the disc, stem, and actuators. Also, in the gate valve, the bonnet allows an opening for the stem.
The gate valve bonnet is joined to the body using threads, bolts, or welding. Some valve bonnets are designed to be merged with the body (bonnetless valves), and bonnets are usually made in the same material as the valve body.
The gate valve trim comprises the valve disc, gland sleeve, gland packings, back seat, valve stem, and valve seat. These are parts that have contact with the flow medium. The valve trim parts control the operation of the valve.
Valve Stem
The stem is responsible for the control of the disc. When the stem is rotated, it relays this motion to the disc by lifting or dropping it. The gate valve stem is joined to the actuator (sometimes through the yoke) or manual handling machine on the top end and the valve disc on the other end to facilitate control.
Valve Seat
The gate valve seat is a resting point for the valve disc to which it is sealed. While some valves have one seat, the gate valve has two seats, one on each end of the pipe flanges. If the disc and valve seat are not sealed properly, it may cause leakages in the valve.
Valve Backseat
The gate valve backseat holds the stem in the valve open position. It also restricts fluid from going up to the packing chamber and the surface.
Valve Disc
The gate valve disc is the part of the valve which performs the function of allowing or restricting flow through the pipeline. It blocks the fluid pressure from moving from one end to another. The disc rests on the valve seat to which it is sealed.
Gland Packings, Sleeve and Yoke
The gland packings prevent leakages from the stem and are usually in a stuffing box. The gland sleeves keep the gland packings in the box.
The yoke connects the actuator to the stem. They are sometimes merged with the bonnet to manufacture several valve designs. The yoke is also called arms.
The gate valve operation is in many ways similar to the operation of most valves. The hand wheel or actuator is controlled to rotate the stem, which controls the gate. For the handwheel, the wheel is turned in several revolutions before the gate valve can be fully open from a closed position or fully closed from an open position.
Control using the actuator is easier as it requires no user at the location, only an actuator system (pneumatic or electric) must be on site. By raising the gate to a fully open position, the valve allows the media to flow through the pipeline without obstruction.
Closing and sealing the pipe to the valve seat retains the flow pressure and restricts the flow of the media beyond the gate. The flow rate of the media experiences erratic change as the gate valve is closed, resulting in an unpredictable relationship between the valve and fluid flow rate.
Fluid pressure and flow against the gate wear out the seat and gate. Gate valves should not be used for flow regulation as the constant flow hastens the damage to the gate and seat.
Installing gate valves should be done properly to increase the service life of the gate valves and to ensure their proper operation. Here are some installation practices to be followed while installing gate valves:
Installation of the gate valve, the flange must be at room temperature.
While valves can be installed in any form, flat or upright, it is advisable to install them in an upright form for easy hand-wheel access.
Ensure that during installation, the pipe flanges are spaced so that there is enough space for the valve to be inserted or removed during servicing.
Welding jobs should be completed before the installation of the gate valve.
Sludges and waste residues in the pipeline must be washed away before the valves are installed.
The flange and valve should be properly aligned, and the pipe handling of the weight of the valve should be checked.
The materials of the gate valve parts should be checked to ensure no damage was done during transportation or storage.
The bolts connecting the valve to the pipes should be tightened properly, and the pressure should be equally distributed.
The parts of the pipe flanges to contact the valves should be clean and free of residue.
The gate valve should be tested after bolting to ensure the valve is stable in its position.
Below are some essential practices to ensure the valve works effectively and lasts longer.
The pressure in the pipes should be released before maintenance of the gate valves commence.
The pressure in the pipes or valves should be released before commencing maintenance.
The gate valve disc should be replaced from the top by removing the bonnet and the stem before the disc is replaced.
The valve should be cycled regularly when not in use.
The process of removing the valve should occur in reverse of the installation.
In selecting a gate valve suitable for operation in specific conditions, factors such as suitable material, size and design must be considered. Here are some factors to consider in buying a gate valve:
Materials used for the production of gate valves vary with specific conditions. Common materials are cast iron, cast carbon steel, stainless steel, ductile iron, gun metal, bronze, steel alloys, stainless steel, and forged steel.
Key selection criteria of material to use are fluid service and design temperature. Below are some materials used in the creation of the gate valve:
Valve Body
Cast Carbon Steel to ASTM A216 Gr. WCB.
Stainless Steel to ASTM A351 Gr. CF8/8M/3/3M
ASTM A351 Gr. CN 7M
Gaskets
Compressed Asbestos fibre Flat Ring
Graphite Asbestos Flat Ring
SS 304/316/304L/316L Spiral wound with PTFE/CAF/Grafoil Filler.
Trims / Internal Working Parts
Material Grades
Below are some common trim material grades used in the production of gate valves
AISI 410 (SS 410 – 13% Cr. Steel)
AISI 304
AISI 316
AISI 304L
AISI 316L
Hast Alloy B/C
ASTM A351 Gr, CN 7M
With stellite hard face seat and wedge face
Trim materials are grouped and assigned a trim number or combination number. In the chart below, material for a gate valve seat, disc, stem and backseat are specified against a trim number.
From this chart, an order can be made by the trim number. There will be no need to specify any materials for an order of the gate valve trim. This chart is in line with the API 600 specification.
Source: HardHat Engineering
Gland Packing
Graphite (Frafoil) moulded ring.
Graphite Asbestos Rope.
Inconel Braided Grafoil with corrosion inhibitor
Below are codes and standards that are used in the design and selection of gate valves:
Pressure Testing
API 598
Pressure Temperature Rating
API B16.34
Face to Face
ANSI B16.10
Socket Weld End
ANSI B16.25 and B16.11
Screwed End
ANSI B 1.20.1 (BSP/NPT)
This post discussed all you need to know about the gate valve, including its function, parts, installation and maintenance requirements, and what you need to consider before buying an industrial gate valve.
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GATE VALVES
A gate valve, also known as a sluice valve, is a valve that opens by lifting a barrier (gate) out of the path of the fluid. Gate valves require very little space along the pipe axis and hardly restrict the flow of fluid when the gate is fully opened.
A gate valve functions by lifting a rectangular or circular gate out of the path of the fluid. When the valve is fully open, gate valves are full bore, meaning there is nothing to obstruct the flow because the gate and pipeline diameter have the same opening. This bore diameter also determines the valve size.
Gate valves are a common linear valve type found in pipelines, both above and below ground. A gate valve is designed to start and stop the flow of liquid through ducting, allowing users to isolate a section of pipe when required. They are often called water gate valves or sluice valves.
When people ask what is a gate valve, they will often have follow-up requests for more information on what gate valves look like, what parts they include, the differences between various types, and exactly how they work. We will cover all of these areas in the various sections of this guide.
Gate valves usually consist of the valve body itself, which is installed in-line (through-conduit) on a length of pipe, and an attached handwheel actuator used for opening and closing the valve. This multi-turn wheel assembly most often extends above or to the side of the pipe and valve, attached to a bonnet assembly via a stem. It can be turned in one direction to open the valve, and in the opposite direction to close it.
The advantages of a gate valve are that they provide complete shut-off of any water flow for troubleshooting, maintenance and pipe-cleaning tasks. They are also bidirectional, meaning they can be used to block flow in both upstream and downstream directions, and they do not cause significant pressure loss in operation.
Limitations of gate valves in certain scenarios may include the fact that they are not especially quick to open or close. Additionally, they are not designed to throttle or control flow by being partially opened or shut.
This guide is designed to explain in more detail what gate valves are, what they are used for, how they work, and the different types of UK gate valves available to buy online. We will also briefly outline how to use them, as well as providing some clear and concise answers to common questions about gate valves. By the end of the guide, readers will be familiar with what sluice valves are, how they work, and why they are used.
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