Residential, commercial and irrigation pumps have pressure sensors that will contact water with varying pH levels and quality depending on water purification processes and added chemicals.
The opening and closing of system valves, such as solenoids can cause a pressure transient within a water pump above the measurement range in a shockwave. An internal welded restrictor plug, also known as a snubber, can reduce the inside diameter of the sensor’s pressure port so that when the pressure spike hits the face of the plug, it feeds through the hole at a slower pace, dampening pressure spikes before reaching the sensor’s diaphragm. The snubber also reduces the overall length, cost and potential leak points in the system.
In this configuration, the liquid must be free of dirt, lint, iron filings, sand and grit to avoid clogging the plug. Pressure sensing technologies such as thin film, bonded metal foil strain gauge and capacitive with very low signal output can limit the diaphragm travel this way. The user must therefore, install a mesh filter in front of the snubber.
With inorganic, bonded semiconductor technologies, inorganic materials are molecularly diffused onto a metallic surface in the presence of certain gases. The high level of raw output provides significant deranging of the sensing element, allowing the use of large cavities without clogging. With deranging, pressure sensors with 350 bar sensing element can maintain high, full-range accuracy from 0 to 100 bar and offer over-pressure capabilities of 700 bar. This is useful in compression pumps, on hydraulic fracturing trucks, and during icing conditions on casing and tubing lines.
Bestech Australia supplies a one-piece 316L stainless steel sensing element offering excellent liquid compatibility and durability. A 4-20 milliampere output signal is recommended for transmission lengths of more than five metres in environments with electrical noise. Frequency output signals are also used by niche manufacturers to provide direct pump feedback into a variable frequency drive. With a signal of 1 to 6 kilohertz, pump manufacturers can save electronic component cost.