What is a special purpose valve and what are its types?

A special-purpose valve is a valve that can do certain functions more than the two-way isolation, control, and check. So this type of valve is considered a special purpose valve.

Types of special purpose valves

1. Multiport valves
2. Flush bottom valves
3. Float valves
4. Foot valves
5. Line blind valves
6. Knife gate valves

Multiport valves

A multiport valve is a valve that has more than two ports, these valves are capable to do the operation very quickly and thus the cost can be reduced too. There are three-port, four-port, and five-port valves in the market. The major advantage of a three-way valve is that it can vary the connection of the two supply lines to a common delivery line and flow can be diverted to any of the directions and it can isolate one of the safety valves for the purpose of maintenance. The advantage of a four-way valve is that it can do the reversal of the pump suction and delivery. It can do the bypass, of the strainer or meter and these valves are also capable to do the reversal of flow.

What are the advantages of multi-port valves

• Fewer valves are needed
• Fast and reliable operation
• The piping layout is simplified and thus the economy in fittings
• The chances of incorrect valve operation are very low, so the risk of product mixing is very less
• In order to achieve faster operation, two multi-port valves can be inter-coupled

Flush bottom valve

The flush bottom valves are mostly used in the bottom of the reactor vessels, autoclaves, and other process vessels for landing abrasive, slurry, viscous material, or solid media. The disk is in the closed position and it matches with the bottom of the vessel or the piping and thus it won’t leave any room for hold up or stagnation. The flush bottom valves are of two types and they are valves with disk opening into the tank and valves with disk into the valve. In the first case the stem would push the disk into the tank to drain the liquid and this type can’t be used if there is any internal which blocks the disk movement. The draining of the material would be affected. In the second type, the disk would be pulled down into the valve and it would affect the discharge of the material.

Advantages of Flush Bottom Valves

• Withstands high temperatures, corrosive chemicals, and abrasive slurries
• Enables total drainage from tanks or vessels
• Minimizes residual fluid, reducing contamination risks
• Simplifies cleaning processes
• Designed to prevent blockages and sediment buildup
• Ideal for handling viscous or slurry materials
• Reduces material accumulation areas
• Easier to clean and maintain, crucial for product purity
• Compact size, ideal for limited space at the bottom of tanks or reactors
• Allows full drainage, minimizing waste
• Cost-effective by improving process efficiency
• Provides quick shutoff at the bottom of tanks
• Improves control over process flow, enhancing safety
• Constructed from robust materials like stainless steel

Float valves

The major purpose of a float valve is to control the fluid level in a reservoir. The valve inlet will be connected to the supply pipeline and the outlet will be open to the reservoir. There will be a float with the lever and it would control the piston movement and thus the flow is regulated. Mostly these valves would have threaded ends and they are connected to the valve of the reservoir. There is no need to provide a nozzle with the reservoir, only an opening is required and the liquid level will be below the inlet connection.

Advantages of Float Valves

• Adjustable to different height levels for customized liquid control
• Maintains liquid levels automatically in tanks and reservoirs
• Eliminates the need for manual monitoring and adjustment
• Few moving parts, making it highly durable and low-maintenance
• Reliable operation in various applications without complex mechanisms
• Automatically shuts off flow when the desired level is reached
• Prevents overflow, reducing water wastage and potential damage
• Affordable solution for level control compared to electronic systems
• Low operational and maintenance costs over time
• Does not require external power sources, relying purely on mechanical movement
• Reduces energy consumption, ideal for remote or off-grid installations
• Suitable for various liquids, including water, fuel, and chemicals
• Used in industries such as agriculture, water treatment, and HVAC systems
• Straightforward installation process

Foot valves

Foot valves are a type of check valve and they will be placed in the wet wells of the pump. The foot valves have a larger flow area than the actual pipe size so that there will be less head-loss. These valves can be considered as a type of non-return valve and also it would have strainers and these valves are needed when there is a negative suction in the pump.  The priming fluid of the pump can be hold by the check action of the valve. The suction strainer helps to hold the solids while the pump sucks the fluid. Most of the foot valves are designed in a way that, they have self-tapping male and female threads in order to do the installation easily.  

Advantages of Foot Valves

• Suitable for industrial, agricultural, and residential use
• Allows water to flow in only one direction, preventing backflow
• Helps maintain prime in pumps by stopping the reverse flow of fluid when the pump is off
• Keeps the pump primed by holding water in the suction line
• Reduces wear on the pump, as it does not have to re-prime with each use
• Minimizes the energy needed to re-prime pumps
• Reduces operational costs by maintaining consistent flow and reducing pump strain
• Often equipped with a mesh or screen to filter out debris
• Protects pumps and piping systems from clogs and potential damage caused by particles
• Prevents “dry running” by keeping water in the suction line
• Extends the pump’s life, reducing maintenance and replacement needs
• Simple installation at the end of a suction line
• Can be used with a variety of pumps in multiple applications
• Commonly used in wells, irrigation systems, and water pumping systems

Line blind valves

These valves are used for positive shut-off and replace a spectacle blind, these valves are not like blind plates they are easier to operate and these valves are not expensive. The most common type of line blind valve is the three-bolt/five-bolt line blind valve. There is a single gate line blind valve and this can be power operated or by using a handwheel. A visible wedge line blind valve would provide a full bore opening or positive blinding inside a seat in a three quarter enclosed body. There won’t be any spilling of line residue while changing the wedges and there is no need for line movement when spectacles are changed.

Advantages of Line Blind Valves

• Reduces product loss and process downtime
• Provides a complete, secure shut-off for process lines, ensuring no flow or leakage
• Ideal for isolating sections of piping in critical operations or maintenance tasks
• Allows for quick and safe line isolation, enhancing safety during maintenance
• Reduces risk of accidental leakage or contamination
• Designed for easy manual or automated switching between open and closed positions
• Minimizes the time and effort required for line isolation, especially in large systems
• Few moving parts, leading to less wear and tear
• Low-maintenance solution for long-term line isolation requirements
• Constructed from robust materials to handle corrosive, abrasive, and high-pressure environments
• Often used in chemical, petrochemical, and industrial applications
• Allows maintenance on isolated lines without the need to drain the entire system

Knife gate valve

These valves can handle dirty or contaminated media and these valves are single seated valves so they can only be used for unidirectional operations. These valves consist of two stationary steel plates and both of them have large holes drilled through them. There is a third plate that slides between the stationary plates in order to perform valve operations. If this is open then it won’t give any resistance to the flow. The major advantage of this design is that the ability of the gate to slip through the plate easily. The gate edge is shaped in a way that it can shear the solids and the elastomer seal would keep the solids away from entering the plates when open.

Advantages of Knife Gate Valves

• Suitable for industries like pulp and paper, mining, and sewage treatment
• Designed to cut through slurries, viscous materials, and solid-laden fluids with ease
• Prevents clogging, making it ideal for wastewater, pulp, and mining applications
• Takes up minimal space in piping systems due to its slim design
• Easier to install in tight spaces compared to other valve types
• Provides minimal resistance to flow in the open position, ensuring efficient fluid handling
• Reduces energy consumption and operational costs by maintaining optimal flow
• Simple construction with few moving parts, reducing the likelihood of mechanical issues
• Low maintenance requirements and easy to clean in demanding environments
• Offers a complete shut-off, especially useful for thick or particulate-laden fluids
• Prevents leakage effectively, maintaining system integrity
• Built to withstand abrasive and corrosive media

FAQ on special purpose valves

What is a special purpose valve?

A special purpose valve is a valve designed for specific, often unique applications where standard valves might not be effective. These valves are typically engineered for specialized functions, such as handling high-pressure environments, corrosive materials, or precise flow control. Examples include choke valves in oil and gas production, safety relief valves, and blowdown valves.

What is the function of a special valve?

The function of a special valve is to perform a specific task in challenging or non-standard conditions. This may include handling extreme temperatures, high pressures, corrosive fluids, or delivering highly accurate control. They ensure safe, efficient, and reliable operation in systems that require tailored solutions beyond standard valve functions.

What are special class valves?

Special class valves refer to valves that meet specific industry standards for high-performance applications. They are manufactured with strict adherence to industry codes and classifications, often based on pressure ratings, temperature ranges, or safety requirements. These valves are used in critical applications such as in the chemical, oil and gas, or power generation sectors.

What is a SPV valve?

“SPV” commonly stands for Special Purpose Valve. SPV valves are those designed for specific tasks or conditions in specialized applications. They can vary widely in design, material, and functionality depending on their intended purpose.

What is the full form of SSV valve?

The full form of SSV valve is Surface Safety Valve. It is commonly used in the oil and gas industry to shut off the flow from a wellhead in emergency situations, ensuring safety by preventing uncontrolled release of hydrocarbons. SSVs are a critical part of well control systems.

Refer the below use article links related to valves

• What is a choke valve and what are the functions of the choke valve?
• What is a solenoid valve and what are its types
• What is a pneumatic valve and what is the function of pneumatic valve
• What is a hydraulic valve and what are the types of hydraulic valves
• What is a poppet valve and what does it do
• What is a directional control valve and what are the types of DCV
• What are the types of pressure control valves and how does it work

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