Pressure gauges systems

The PAN was isolated from the numerous side products by gas chromatography on preparatorysized columns and collected by cryogenic trapping. The PAN was then placed in large air canisters, diluted with zero air, and stored in a cold room for future use. Safety precautions are required with this method, because explosive accidents have been reported. The cause of the explosions is believed to be condensation of PANs in vacuum or pressure gauge systems. Like all nitrates, the peroxy nitrate PAN has explosive potential, and care must be taken when handling PAN on metal surfaces. The Stephens synthetic approach illustrated by Reaction 19.7 to Reaction 19.11 was quite successful, and a number of publications on the toxicity of PAN and its chemical and physical properties resulted from the use of the scheme. ... 

To appreciate the action of a drying agent of class (a), let us imagine some anhydrous copper sulphate in an evacuated vessel provided with a pressure gauge, and water is allowed to enter slowly the temperature is assumed constant at 25°. The results may be best expressed by means of a vapour pressure - composition diagram (Fig. 7, 20, 1). The initial system is represented by the point A the pressure will rise along AB until the monohydrate CuS04,H20 commences to form at B. 

Fig. 4. Diagram of a hoUow-fiber ultrafilter filtration system where A corresponds to the retentate reservoir B, circulation pump C, pressure gauge at module inlet D, ultrafilter module E, permeate reservoir F, pressure gauge at module outlet G, value to control module outlet pressure and H, drain...

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

When a system is isolated, it cannot be affected by its surroundings. Nevertheless, changes may occur within the system that are detectable with such measuring instruments as thermometers, pressure gauges, and so on. However, such changes cannot continue indefinitely, and the system must eventually reach a final static condition of internal equilibrium. 

Also ealled the DUH Factor. You ll need to gather information from pressure gauges mounted to the existing system. With the previously mentioned formulas, the Hf and the Hv are estimated in the initial phase when everything is new. The Baehus Custodio method measures the exact Hf and Hv in any existing system. It doesn t matter when it was built. 

Lube oil level in the reservoir should be monitored by a sensing deviee to indieate low lube oil level. Loeal and panel-mounted pressure gauges are neeessary to monitor operation of the lube oil system and must be ineluded in the manufaeturer s seope of supply. The purehaser must distinguish between eontrol room instrumentation and instruments mounted on a stand-alone (loeal) panel. There is also a tendeney to plaee monitoring instruments on auxiliary equipment and piping. While this may eost less, it often eomplieates tlie operator s surveillanee tasks. 

Pressure gauges should be provided at the diseharge of the pumps, the bearing header, the eontrol oil line, and the seal oil system. Eaeh atmospherie oil drain line should be equipped with steel nonrestrietive bull s-eye-type flow indieators positioned for viewing through the side. Viewports in oil lines ean be very useful in providing a visual eheek for oil eontamination. 

A differential pressure switch set to alarm when the pressure drop reaches a predetermined point protects against the loss of oil flow. In addition to the differential pressure switch, a two-way, three-port valve with a pressure gauge is piped in parallel with the differential pressure switch for accurate indication of inlet and outlet oil filter pressure. When a single transflow valve is used with a cooler-filter installation, the differential pressure switch and pressure gauge assembly should span the cooler-filter system. 

Vacuum pressure Gauge pressure in psi (gpsi) is the amount by which pressure exceeds the atmospheric pressure of 14 psi (negative in the case of vacuum). The absolute pressure (psia) is measured with respect to zero absolute vacuum [29.92 in. (101 kPa) Hg], In a vacuum system it is equal to the negative gage pressure subtracted from the atmospheric pressure. (Gauge pressure + atmospheric pressure = absolute pressure) (1 in. Hg = 0.4912 psi of atmosphere on a product) (1 psi = 2.036 in. Hg). 

The efficiency of power generation is significantly reduced by any deposits formed on the turbine blades by BW carryover and severe turbine damage may also result. Tiirbine efficiency also is reduced by demands for output that exceed the rated maximum and by extended operation beyond the maintenance period or design life. Additionally, errors in steam flow meters, thermometers, and pressure gauges, and so forth cause the control system to regulate the generation of electricity at some further reduced level. 

Although a pressure gauge is more commonly used to measure the pressure inside a laboratory vessel, a manometer is sometimes used (Fig. 4.5). It consists of a U-shaped tube connected to the experimental system. The other end of the tube may be either open to the atmosphere or sealed. For an open-tube manometer (like that shown in Fig. 4.5a), the pressure in the system is equal to that of the atmosphere when the levels of the liquid in each arm of the U-tube are the same. If the level of mercury on the system side of an open manometer is above that of the atmosphere side, the pressure in the system is lower than the atmospheric pressure. In a closed-tube manometer (like that shown in Fig. 4.5b), one side is connected to a closed flask (the system) and the other side is vacuum. The difference in heights of the two columns is proportional to the pressure in the system. 

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