Pressure Regulators Information
Pressure regulators are used to reduce the pressure in a system to a lower pressure or to regulate system pressure at the desired value. Among the types of pressure regulators are back pressure, vacuum pressure, differential pressure, pressure-reducing and regulators for specific kinds of fluids like oil and fuel. The most important parameter to consider when specifying pressure regulators is the regulating or adjustment range. This is the limit of adjustment control on the pressure range.
Common media types include:
- Fuel and oil
- Hydraulic fluids
Pressure regulators reduce high pressure on the input side to a lower controlled pressure level on the output side. They maintain consistent pressure within a system, although they experience some level of pressure drop, called droop, as the flow increases. Pressure regulators do not control flow; they are used to control delivery pressure only.
There are three basic operating components in regulators.
The loading mechanism for pressure regulators affects the setting of the regulator and the delivery pressure. The most common design of the loading mechanism is a spring. When a pressure regulator’s adjustment knob is turned, the loading mechanism is compressed. Force placed on the spring is transmitted to the sensing element and the control element. These parts function together to achieve the desired outlet pressure.
Sensing elements in pressure regulators react to the force placed on the loading mechanism as well as the difference between the inlet and outlet pressure. Most pressure regulators rely on a diaphragm to act as the sensing element. These diaphragms may be made of elastomers or metal depending on the application. The sensing element combined with the loading mechanism sends the change in force to the control element.
The control element is a valve that ultimately reduces the inlet pressure to outlet pressure by incorporating the feedback it receives from the other parts of the system. When the regulator’s control knob is adjusted, the loading mechanism is compressed or expanded depending on the desired pressure. This in turn changes the force on the sensing elemen,t which then further adjusts the force on the control element, causing it to move away from or towards the pressure regulator’s valve seat. In turn, the orifice becomes larger or smaller in order to provide the pressure required.
Pressure balancing valves maintain even pressure when there is a pressure drain on the system. EFor example, a balancing valve prevents surges of hot or cold water in a water supply system when one of the lines is used.
General purpose regulators are designed for typical industrial use. These generally operates only above atmospheric pressure.
High pressure regulators are rated for inlet pressures higher than general purpose, typically over 1000 psi.
Low pressure regulators have special design characteristics for precise control of pressures typically below 15 - 20 psi.
In a vacuum or compound regulator, also known as an absolute pressure regulator, the regulator is designed to control fluid below atmospheric pressure.
A differential or bias regulator maintains a pressure differential between two locations in the system.
In a pressure-reducing regulator pressure-reducing valves are used to provide a sub-circuit with a supply of fluid at a pressure, which is less than the pressure in the main circuit.
A point of use regulator is designed to attach at or near a tool or device.
Pressure reducing valve schematic. Image credit: Stack Exchange
The body of pressure regulators can be made from acetal, aluminum, brass, bronze, cast iron, steel, stainless steel, and zinc. Common connectors can be from 1/8” NPT to 2” NPT, British standard pipe thread and metric pipe thread.
Mounting types include cartridge, pipe or line mount, stacked or switch mount, and subplate or manifold mount.
- Integral pressure gauges display system pressures.
- Integral filters are for the fluid intakes.
- Integral lubricators are for valve operation.
- Pressure reliefs are a provision for bleeding off pressure at regulator.
- Tamper-proof pressure regulators have a security device to prevent unwanted adjustment (lock, removable adjustor, etc.).
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