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Many of the products we sell were originally developed for a new customer’s application and have now become mainstream products in our range. As innovators and leaders in the high pressure pumps market we are always looking for opportunities to design and develop new products to meet our customers’ requirements. 

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Tel: 01252 622031

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Technical

We are often asked by customers to explain various types of pressure protection devices used in high pressure systems. Because our pumps they are truly positive displacement, they will continue to pump liquid even when the outlet is restricted or completely closed off, so this flow has to go somewhere!
To control the pressure you should fit either a Pressure Regulator Valve or an Unloader Valve, as a primary pressure protection and control device. Both of these have a Piston that is held against a Seat by a pre-loaded spring. When the force of the liquid pressure in the system acting on the area of the piston overcomes the set spring load, the piston lifts off its seat to allow low-pressure liquid to flow from the bypass connection. The piston will then ‘float’, constantly lifting and falling, varying the bypass flow to maintain a constant pressure in the system and dissipating surplus pressure energy across the seat.
Even if a downstream pipeline is completely closed, the Regulator or Unloader will bypass the full pump flow to regulate the pressure and protect the pump, drive motor, pipes and other components. But this is where a Regulator and an Unloader differ:
An Unloader Valve is only used in pressure cleaning equipment fitted with one or more trigger guns and is employed to drop the pressure at the pump by around 90% when no flow is required. This takes the load off the pump, pipework and motor or engine. The pressure shock wave created when the trigger gun suddenly closes is reflected back through the outlet pipework. In the most common type of Unloader, this moves the valve to a fully-open position, bypassing all the pump flow at low pressure. High pressure remains trapped in the pipe between the Unloader and the trigger gun, holding the unloader fully open, until the trigger is squeezed and flow is instantly resumed. The Unloader Valve (sometimes referred to as a Regulating Unloader) then functions in a similar way to a Pressure Regulator.
Cat Pumps Pressure Regulator Valves have excellent pressure control characteristics and will hold a virtually constant pressure irrespective of the proportion of the pump flow that is being bypassed. A Pressure Regulator Valve can be used in any system, including pressure cleaning equipment fitted with wash-down trigger guns, but also industrial processes, hydrostatic pressure test equipment, reverse osmosis desalination plants etc. that do not incorporate quick-closing guns or valves. Cat Pumps Pressure Regulators provide smooth stable operation, free from chatter, and most of our valves have been upgraded to our latest conical piston and seat design to minimise noise, wear and cavitation giving long dependable life.
We recommend that your Cat Pump and regulating valve are matched such that a minimum of 5% of the pump flow is always being bypassed so the valve piston is held slightly off its seat.
We recommend that all high pressure systems also include a secondary protection device, normally a Relief Valve. This gives added protection should the primary regulator or unloader valve fail to operate and will only open if a fault occurs e.g. debris in the system blocks the primary valve, or unauthorised personnel tamper with equipment settings.
A Relief Valve works much like a regulator valve but commonly does not provide such accurate pressure control. The pressure at which the valve starts to open will normally be set 15% above the system operating pressure. A Relief Valve should never open during normal system operation.
Cat Pumps supply a wide range of Pressure Regulating Valves, Unloader Valves and Relief Valves and we can offer the correct size and type for your system. Valves supplied loose as accessories are not adjusted and must be set by the installer. If we incorporate valves into a complete Power Unit or skid system, we set these during production.

Pressure Regulator Valves

We are often asked by customers to explain various types of pressure protection devices used in high pressure systems. Because our pumps they are truly positive displacement, they will continue to pump liquid even when the outlet is restricted or completely closed off, so this flow has to go somewhere!

Valves

To control the pressure you should fit either a Pressure Regulator Valve or an Unloader Valve, as a primary pressure protection and control device. Both of these have a Piston that is held against a Seat by a pre-loaded spring. When the force of the liquid pressure in the system acting on the area of the piston overcomes the set spring load, the piston lifts off its seat to allow low-pressure liquid to flow from the bypass connection. The piston will then ‘float’, constantly lifting and falling, varying the bypass flow to maintain a constant pressure in the system and dissipating surplus pressure energy across the seat.

Even if a downstream pipeline is completely closed, the Regulator or Unloader will bypass the full pump flow to regulate the pressure and protect the pump, drive motor, pipes and other components. But this is where a Regulator and an Unloader differ:

  • An Unloader Valve is only used in pressure cleaning equipment fitted with one or more trigger guns and is employed to drop the pressure at the pump by around 90% when no flow is required. This takes the load off the pump, pipework and motor or engine. The pressure shock wave created when the trigger gun suddenly closes is reflected back through the outlet pipework. In the most common type of Unloader, this moves the valve to a fully-open position, bypassing all the pump flow at low pressure. High pressure remains trapped in the pipe between the Unloader and the trigger gun, holding the unloader fully open, until the trigger is squeezed and flow is instantly resumed. The Unloader Valve (sometimes referred to as a Regulating Unloader) then functions in a similar way to a Pressure Regulator.

  • Cat Pumps Pressure Regulator Valves have excellent pressure control characteristics and will hold a virtually constant pressure irrespective of the proportion of the pump flow that is being bypassed. A Pressure Regulator Valve can be used in any system, including pressure cleaning equipment fitted with wash-down trigger guns, but also industrial processes, hydrostatic pressure test equipment, reverse osmosis desalination plants etc. that do not incorporate quick-closing guns or valves. Cat Pumps Pressure Regulators provide smooth stable operation, free from chatter, and most of our valves have been upgraded to our latest conical piston and seat design to minimise noise, wear and cavitation giving long dependable life.

We recommend that your Cat Pump and regulating valve are matched such that a minimum of 5% of the pump flow is always being bypassed so the valve piston is held slightly off its seat.

We recommend that all high pressure systems also include a secondary protection device, normally a Relief Valve. This gives added protection should the primary regulator or unloader valve fail to operate and will only open if a fault occurs e.g. debris in the system blocks the primary valve, or unauthorised personnel tamper with equipment settings.

A Relief Valve works much like a regulator valve but commonly does not provide such accurate pressure control. The pressure at which the valve starts to open will normally be set 15% above the system operating pressure. A Relief Valve should never open during normal system operation.

Cat Pumps supply a wide range of Pressure Regulating Valves, Unloader Valves and Relief Valves and we can offer the correct size and type for your system. Valves supplied loose as accessories are not adjusted and must be set by the installer. If we incorporate valves into a complete Power Unit or skid system, we set these during production.