What is a Pressure Regulator?
A pressure regulator is a device that reduces a high input pressure to a regulated lower output pressure. It’s designed to control the pressure of liquids or gases in a system. Pressure regulators also help to keep the output pressure constant, even while the inlet pressure fluctuates.
Pressure regulators are most commonly used in several households and commercial applications, such as moderating propane in gas grills, oxygen in hospital equipment, and compressed air delivery in industrial applications.
The fundamental feature that all of these applications have in common is pressure control, which involves switching from a higher source pressure to a reduced constant output pressure.
Working Of Pressure Regulator
A pressure regulator serves the primary purpose of reducing the inlet pressure to a lower desired outlet pressure. The main function of the pressure regulator is to consistently maintain this outlet pressure, even when there are variations in the inlet pressure.
Essentially, a pressure regulator ensures that the fluid flow passing through it matches the requirements while keeping the output pressure constant. When the demand for fluid reduces, the regulator reduces the flow accordingly, and when the demand surges, it increases the flow to prevent a drop in the controlled pressure due to a fluid deficiency within the system.
Components of a Pressure Regulator
The following are the components of a standard pressure regulator:
- poppet valve
- Membrane or diaphragm
- Inlet and outlet valves
1) Poppet Valve
The poppet valve is one of the most important parts of the pressure regulator. It is installed to reduce the pressure of the system.
2) Loading Element
It governs the operation of the sensing element, which in turn controls the valve’s operation. The level of spring force is customizable, and it dictates the resulting outlet pressure.
3) Sensing Element
The piston and diaphragm work as the sensing element. The piston design is ideal for robust and high-pressure applications. But they can be slow to respond because of the friction between the regulator body and the pinion seal.
Diaphragms are ideal for higher-accuracy applications. They have lower friction compared to pistons. Elastomer or a thin disc type of material is used for the construction of diaphragms.
Types of Pressure Regulators
Pressure regulators are broadly classified into two categories:
- Self-operated or direct-operated regulator
- Pilot operated regulator
1) Direct Operated Pressure Regulator
Direct operator regulator is one of the most common types of pressure regulator. They often work at lower set pressures, typically less than 0.07 bar (1 psi), and therefore they achieve higher accuracy. They can have 10-20 percent accuracy levels at more significant pressures of up to 35 bar (500 psi).
Direct-operated regulators are self-contained, which means they don’t need an external sensing component at the output to function correctly. They are made out of a spring-driven valve controlled entirely by a diaphragm assembly.
The diaphragm is activated by the energy or pressure of the flowing media. Increased downstream pressure pushes the diaphragm, which compresses the spring and closes the valve stopper. As a result, the valve closes.
As the downstream pressure decreases, the spring force exceeds the force of the medium that acts on the diaphragm, opening the valve.
2) Pilot Operated Regulator
These regulators are appropriate for situations with considerable variation in flow rates, intake pressure fluctuations, or declining inlet pressure conditions, such as when gas is delivered in cylinders or tiny storage tanks. In such conditions, this regulator allows for precise pressure regulation.
Pilot-operated regulators are usually one or two-stage devices. For relatively small pressure reductions, a single-stage regulator is ideal. The latter isn’t ideal where intake pressure or flow rates fluctuate a lot.
A double-stage regulator is the most popular form of the pilot-operated regulator. The first stage consists of a spring-activated pilot that regulates the pressure on the primary regulating valve’s diaphragm. There is no flow downstream as long as the medium pressure on the spring-actuated pilot is low.
As the pressure rises, the spring compresses and the pilot valve opens, resulting in a difference in pressure between the inlet of the primary regulating valve and the output valve. This pressure difference opens the main operating valve, allowing flow at a lower pressure via the outlet valve.
Double-stage pilot-operated regulators provide precise regulation for an expansive range of pressures and capacities. Because small passages and pores can become clogged, these regulators should only be used with clean fluids or gases.
Functions of Pressure Regulator
In addition to lowering input pressures, a pressure regulator also performs the following functions:
1) Act as pressure relief valves and back pressure regulators
When the set pressure is reached, a pressure relief valve restricts system pressure to a predetermined maximum by channeling some or all of the fluid or gas flowing from the pump towards the tank.
A backpressure regulator maintains a constant input pressure by varying the fluid or gas flow with respect to the variations in input pressure.
2) Act as pressure switching valve
These are commonly found in pneumatic logic systems. They can either be 2/2-way switching valves or 3/2-way switching valves.
3) Constant output pressure
If the input pressure fluctuates, the pressure regulator will attempt to keep the output pressure at a constant pressure unless the input pressure drops too low.
Applications of Pressure Regulators
- Domestic: Pressure regulators are used in different residential applications, such as heating furnaces, gas ovens, gas grills, pressure vessels, and pressure cookers.
- Compressed Air: Pressure regulators are used in applications such as powering air-actuated tools, cleaning, inflating tires, and other industrial, commercial, and workshop applications.
- Welding and cutting: They are installed in oxy-acetylene welding to provide gas at the required pressure from storage cylinders.
- Gas-powered vehicles: They are used to supply the engine with pressurized gas.
How to Choose a Pressure Regulator?
Pressure regulators are available in varying sizes and designs, so you always want to consider your system requirements and unique needs before making up your mind.
Some of the critical aspects to consider are your operating pressure range, transmission medium (i.e., fluid or gas), operating temperature range, material requirements, and accuracy required.
If you are unsure of the exact system specifications and requirements, seek professional advice from a trusted and knowledgeable third party.
What is the function of the pressure regulator?
The main function of the pressure regulator is to reduce a high input pressure according to the system’s desired pressure. It is designed to control the pressure of liquids or gases in a system.
What are the types of the pressure regulator?
- Direct-operated regulator
- Pilot operated regulator
Do pressure regulators control flow?
No, pressure regulators are not intended to operate as flow controllers. They just control the pressure of the flowing fluid.