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The low-pressure sensitivity of hot-cathode gauges is limited by the photoelectric effect. Electrons hitting the grid produce X-rays that produce photoelectric noise in the ion collector. This limits the range of older hot-cathode gauges to 10 −8 Torr and the Bayard–Alpert gauges to about 10 −10 Torr.
Automatic calibration - A U.S. serviceman using a 3666C auto pressure calibrator. An automatic pressure calibrator [13] is a device that combines an electronic control unit, a pressure intensifier used to compress a gas such as Nitrogen, a pressure transducer used to detect desired levels in a hydraulic accumulator, and accessories such as ...
Instruments used to measure and display pressure mechanically are called pressure gauges, vacuum gauges or compound gauges (vacuum & pressure). The widely used Bourdon gauge is a mechanical device, which both measures and indicates and is probably the best known type of gauge.
The gauge may be used for pressures between 0.5 Torr to 1×10 −4 Torr. Below 5×10 −4 Torr, a Pirani gauge has only one significant digit of resolution. The thermal conductivity and heat capacity of the gas affects the readout from the meter, and therefore the apparatus may need calibrating before accurate readings are obtainable.
The efficiency of the chamber can be further increased by the use of a high-pressure gas. Typically a pressure of 8-10 atmospheres can be used, and various noble gases are employed. The higher pressure results in a greater gas density and thereby a greater chance of collision with the fill gas and ion-pair creation by incident radiation.
Gauges for measuring pressure in the range 20–30 standard atmospheres (15,000–23,000 mmHg) have been built. [13] A 23-metre-tall mercury column is difficult to read and suffers from inaccuracies caused by different parts of the column being at different temperatures. A more compact mercury pressure gauge suitable for high pressure was built ...
A burst low pressure hose will usually lose gas faster than a burst high pressure hose, as HP hoses usually have a flow restriction orifice in the fitting that screws into the port, [16]: 185 as the submersible pressure gauge does not need high flow, and a slower pressure increase in the gauge hose is less likely to overload the gauge, while ...
Small pressure pan application. A third test method to determine if ductwork is leaking to the outside is to use a pressure pan, which is a register cover with a pressure tap for a hose connection. With the house pressurized (or depressurized) to 50 Pa (-50 Pa) using a blower door, a pressure gauge is attached to the pressure pan by means of a ...