Diaphragm pressure gauge

Eveiy effort should be made to eliminate direct (Bourdon-type) pressure gauges. Diaphragm pressure gauges constructed of appropriate corrosion-resistant materials are preferred. Flow limiters should be used to limit flow in case of loss of integrity... 

C, diaphragm pressure gauge, measured range 30-70°C, Ambrose et al. 1976)... 

Liquid-filled gauges are prone to spills and the inclusion of bubbles and before use must be carefully levelled and zeroed. Diaphragm pressure gauges avoid these problems but need to be checked for accuracy from time to time. 

In a diaphragm pressure gauge the elastic deflection of a circularly clamped metal disk is transferred to a pointer. Such devices are suitable for measuring ranges of 0-0.5 mbar and 0-70 bar [3]. For vacuum applications the range is 0-0.5 mbar and 0-1 bar vacuum. They are also suitable for differential pressure measurement if both sides of the diaphragm are connected with the respective measuring points. 

Bourdon tube and diaphragm pressure gauge designs are easily calibrated and have standard designs. 

Fig. 11. Diaphragm-box systems, open and closed types, used where pressure gauges cannot be located at the minimum tank level.

Strain-gauge pressure transducers are manufactured in many forms for measuring gauge, absolute, and differential pressures and vacuum. Full-scale ranges from 25.4 mm of water to 10,134 MPa are available. Strain gauges bonded direc tly to a diaphragm pressure-sensitive element usually have an extremely fast response time and are suitable for high-frequency dynamic-pressure measurements. 

The best-known design of a diaphragm vacuum gauge is a barometer with an aneroid capsule as the measuring system. It contains a hermetically sealed, evacuated, thin-walled diaphragm capsule made of a copper-beryllium alloy. As the pressure drops, the capsule diaphragm expands. 

Many control problems can be better solved with a diaphragm controller. The function of the diaphragm controller (see Fig. 3.27) can be easily derived from that of a diaphragm vacuum gauge the blunt end of a tube or pipe is either closed off by means of an elastic rubber diaphragm (for reference pressure > process pressure) or released (for reference pressure < process pressure) so that in the latter case, a connection is established between the process side and the vacuum pump. This elegant and more or less automatic regulation system has excellent control characteristics (see Fig. 3.28). 

Those that are based on the measurement of the distortion of an elastic pressure chamber (mechanical pressure gauges such as Bourdon-tube gauges and diaphragm gauges)... 

Sanitary diaphragm-style pressure gauges should be used when possible, as they are very cleanable. When pressure gauges are installed in process piping, the diameter should be less than 6D. 

Make sure that the outlet needle value is closed, and then slowly turn the handle on the diaphragm valve clockwise until the outlet gauge reads about 2 psi. Keep in mind that the outlet pressure gauge reads overpressure, i.e., psi atoue atmospheric pressure. 1 psi = 0.068 atm = 51.7 Torr. 

K. Diaphragm-type pressure gauge L Steam-sterilizable sample port... 

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