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Glossary
Analogue Signal
A scaleable input/output signal. It is used when a measurement will vary i.e 4-20mA signal from a process analyser or flow meter.
API 675 (American Petroleum Institute Standard No 675)
Certifies that a pump has passed performance tests to give greater accuracy and reliability.
ATEX (ATmospheres EXplosive)
Mandatory from 1st July 2003, this European Directive effects all manufacturers and users of electrical and mechanical equipment for use in hazardous areas. For more information please check out our web links page
Back Pressure
Pressure which a pump must overcome in order to dose at the point of injection. Measured in bar.
Dead Head
When a pump tries to operate against a closed valve or other condition that will prevent discharge.
Digital Signal
An on/off input/output signal. Could be a contact closure or pulse from a flow meter.
EExD explosion-proof system
A motor or electronic device certified suitable for use in a zone-classified area, making the system explosion-proof and suitable for use in hazardous areas.
Electronic controller
A complete control system that provides a feed-back to the pump to maintain the correct chemical dosage. A controller can make the system more efficient and, maybe, more economical. On the Signal S200 (EMP2 and EMP3) series pumps, the controller can be integrated with redox or pH control.
Flooded Suction
Situation where a pump is positioned below the level of the liquid to be pumped i.e. the inlet of the pump is under flooded suction.
Flow checker (S100 only)
A unique flow metering device that provides remote or local feedback on actual pump output.
Flow meter (S200 and S300)
An instrument which measures flow, from which a output can be used for proportional dosing, or a device which measures actual pump discharge volume.
Flow switch
Provides a positive indication that the pump is operating and the fluid is flowing. show picture
Foot valve, strainer and injection fitting
Assists in maintaining the prime of the pump under suction lift conditions and prevents large solids from entering the pump. This maintains back pressure on the pump, even when the pump is dis-connected. It generally assists with the control of flow and also injects into the centre of the flow. Additionally, it serves as an anti-syphon device and non-return valve.
Hydraulic Diaphragm
A diaphragm which is actuated by a hydraulic fluid. Suitable for continuous operation, accurate and usually contains integral relief valve.
Mechanical Diaphragm
A diaphragm which is actuated by a rod or plunger. More simple and economical in comparison to hydraulic diaphragm.
Multifunction valve
Combines the function of the pressure loading and pressure relief valve into a single unit that saves on installation cost and provides anti-syphon protection and drain facility. Separate pressure loading and pressure relief valves are also available.
Plunger Pump
A pump without a diaphragm, where the movement of a plunger directly pumps the liquid. This type of pump will deliver linear discharges at high back pressures.
Pressure loading valve
On systems operating on a pressure of less than 1 bar, the valve maintains back pressure on the pump and ensures that accurate flow control is sustained. It also serves as an anti-syphon device.
Pressure relief valve
A safety device that protects the pump and system from damage if over-pressure occurs.
Prime
To ensure that a pump head is filled with liquid rather than air or gas. An air locked pump will not discharge.
Pulsation damper
Fitted to the suction or discharge side of the pump, it reduces pressure surges on arduous applications such as long dosing lines.
Solenoid Pump
Pump in which the actuating mechanism is a solenoid, rather than a motor. A solenoid is pulse driven forward and spring returned.
Specific Gravity
The density of a product related to water. SG of water is 1
Suction lance
Combining a foot valve and strainer, the suction lance is inserted into the suction vessel, where it ensures maximum draw-down. It allows low level switching to stop the pump and can provide low level cut-out. A further option of additional low-level warning may be incorporated.
Suction Lift
Situation where a pump is positioned above the product to be pumped, requiring the pump to lift the liquid. The maximum suction lift is stated in pump specifications, but it should be remembered that this figure relates to water. For maximum suction lift divide lift height by specific gravity.
Tank and pump sets
Signal markets a range of pump and tank sets - effectively a complete single-sourced chemical delivery system that can be bunded if required and are delivered to site ready to install, complete with matched pipes and valves. They are pre-engineered, pre-tested systems available in a range of tank sizes, up 4,500 litres capacity - although larger sets can also be engineered.
Tubing
Available in a wide range of diameters and materials, including PVDF, PFA, PE, nylon-reinforced PVC and others on request.
Viscosity
A measure of a liquid's resistance to flow i.e. thickness. Unit of measurement is usually Poise or Centi poise (derived from the French Physicist Jean Louis Poiseuille 1799-1869). Example peanut butter at 20 degrees C 250,000 cPs, Honey 2000-3000 cPs.
VSD motor
A three-phase motor suitable for operation from a variable frequency inverter supply.
Wide range of head materials
For the higher specification S300 series process pumps, a wide choice of pump head material is available. This includes PVC, PP, PVDF, PTFE, stainless steel, carpenter 20 and hasteloy.
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