Function of electric contact pressure gauge in water pump control system

The electric contact pressure gauge is similar to the ordinary pressure gauge, which is based on the fact that the spring tube in the measuring system is forced to produce corresponding elastic deformation and displacement at the end of the spring tube under the pressure of the measured medium, and the measured value is indicated on the dial by the indicator on the fixed gear (together with the contact) driven by the pull rod through the gear transmission mechanism and amplified. The difference is that the electric contact pressure gauge is equipped with auxiliary contacts, which are usually used in conjunction with corresponding electrical devices (such as relays and frequency converters). When it contacts with the contacts (upper limit or lower limit) on the set pointer, the circuit in the signal system can be disconnected or connected, and various gases and liquid media with measured (controlled) pressure can be automatically controlled and sent signals (alarms) through the instrument.

Electric contact pressure gauges are widely used in petroleum, chemical industry, metallurgy, power station, machinery and other industrial departments, or in the matching of electromechanical equipment to measure the pressure of various fluid media without explosion danger, and now they are also widely used in water supply and drainage systems. Among them, the supplementary pressure pump and pressure stabilizing pump in the fire protection system use electric contact pressure gauges to control the start and stop of the pumps to maintain the pressure stability in the pipe network within the required range.

Under normal circumstances, the electric contact pressure gauge is connected to the water outlet pipe at the back end of the pump through the buffer pipe, connected to the pressure signal control line and connected to the secondary control loop of the pump. Theoretically, the control system is in an automatic state. When the pressure in the pipe reaches the pressure indicated by the low pointer, the pump control system obtains the pump start signal and the pump starts. When the pressure in the pipe rises to the pressure indicated by the high pointer, the pump control system obtains the pump stop signal and the pump stops.

During the actual debugging, it is found that the hotel system has a large pipe network, and the power, lift and flow rate of the pumps used in fire fighting are large. Even if the buffer pipes are added, the pressure in the pipes can't be avoided when the pumps are started and stopped, which directly leads to the large and frequent shaking of the pressure gauge pointer. The pump control system keeps receiving the signals of starting and stopping the pumps, and the pumps will start and stop frequently, which can't achieve a good pressure stabilization effect and may easily damage the pressure gauge, which may seriously affect it.

What is a vacuum pressure gauge

The main features of vacuum pressure gauge are as follows:

(1) stable performance, high measurement accuracy and fast reaction speed.

(2) It is an absolute vacuum gauge, and the one with an accuracy of 0.5 or above can be used as a standard vacuum.

(3) The total pressure is measured, including the pressure of gas and steam.

(4) The measurement results have nothing to do with the types, compositions and properties of gases.

(5) In the process of measuring M, the suction and discharge of the vacuum gauge itself are very small, which will not affect the measured atmosphere.

(6) There are no high-temperature parts in the vacuum gauge, which will not decompose the oil vapor.

(7) If it is made of corrosion-resistant materials, the pressure of corrosive gas can be measured.

(8) The structure is firm and easy to seal and install.

(9) The operation is simple and does not need to be adjusted, but it needs to be checked regularly.

Precautions:

Vacuum pressure gauge is a commonly used measuring instrument, which has certain applications in many fields. There are also many problems that users need to pay attention to when using vacuum pressure gauges. For example, the range of measurement, temperature and other issues:

1. The operating environment temperature of the instrument is -40~70℃, and the relative humidity is not more than 80%. If it deviates from the normal operating temperature by 20℃, the additional temperature error shall be included. 2, the instrument must be installed vertically, and strive to keep the same level with the measuring point. If the difference is too high, it is included in the additional error caused by the liquid column, so it is unnecessary to consider when measuring gas. When installing, block the explosion-proof port at the back of the case to avoid affecting the explosion-proof performance.

3. The measuring range of the instrument in normal use: it shall not exceed 3/4 of the upper measuring limit under static pressure and 2/3 of the upper measuring limit under fluctuation. Under the above two pressure conditions, the minimum measurement of large pressure gauge should not be less than 1/3 of the lower limit, and the vacuum part should be used completely when measuring vacuum.

4. In case of instrument pointer failure, loose internal parts, failure to work normally, etc., it should be overhauled, or the manufacturer should be contacted for maintenance.

5, the instrument should avoid vibration and collision, so as to avoid damage.

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