The Pressure Line
An important note about pressure in the line, to determine whether the pressure reading is constant or she will fluctuate. Maximum pressure where gage constantly works should not exceed 75% of full scale range. For best performance, the sensors should be graduated to twice the normal system operating pressure.
This reserve power ensures the safety factor to prevent overpressure damage. It also helps to avoid a permanent set Bourdon tube. For applications with significant fluctuations in pressure is an additional profit, is especially important. In General, the lower the Bourdon tube pressure, the greater the excess pressure percentage it will absorb without damage. The higher the Bourdon tube pressure, the less the excess pressure he will quietly absorbing.
Ripple leads index flutter, that makes difficult to gauge. Pulsation can also significantly reduce the gage of life by causing excessive wear movement of the gear teeth. Pulsating pressure is defined as the change in pressure of more than 0.1% of full scale per second.
Following are terms that occur frequently and suggested ways of dealing with them.
The terminator is a cheap means of struggle with the pulsation of the problem. This device reduces the opening pressure. Reduction opening allows less changes in pressure to achieve Bourdon tube in a given time interval. This damping device protects Bourdon tube at curbing excessive pressure surges. It also improves gage decrease readability index flutter. When you specify sensors limiters, indicate whether the pressure environment of liquid or gas. Medium-determines the size of the hole. In addition, the limiters not recommended for dirty liquid line. Dirty materials in line can score a hole. For such conditions, diaphragm seals should be specified.
Needle valve is another means of processing ripple when used between a line and a gage. Cm. Fig. 1-25. Throttle down to the point where ripple ceases to register at gage. In addition, the advantage for precise control, needle valves also offer a complete shutoff, an important factor of security in many applications. Use the needle valve can significantly extend the life of gage, allowing it to be used only when reading the need. Liquid sensors another very effective way of solving line ripple problems. Because the movement is constantly submerged in lubrication fluids, reaction to pulsating pressure dampened and pointer flutter is practically eliminated.
Silicone oil, treated movements dampen vibration, caused by line pressure pulsations and/or mechanical fluctuations. Silicone oil, used for movement, bearings, gears, acts as a shock absorber.
This expands gage life, providing accuracy and clarity...