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Why should the refrigeration shut-off valve be low and high?

放大word体  缩小word体 Release date:2018-05-31  Views:48
Core Tip:The cut-off valve, also known as the cut-off valve, belongs to the forced sealed valve, which is one of the truncated va

The cut-off valve, also known as the cut-off valve, belongs to the forced sealed valve, which is one of the truncated valves. There are three kinds of connections: flange connection, threaded connection and welding connection.

China's valve "three to" has been stipulated that the flow of the cut-off valve should be adopted from top to bottom, so the installation will be directional.

This type of cut-off valve is very suitable for cutting or regulating and throttling.  Because the valve stem opening or closing the stroke is relatively short, and has a very reliable cutting function, and because the change of the valve seat opening is proportional to the stroke of the valve, it is very suitable for the adjustment of the flow.

The globe valve is designed for low inlet and outlet height. The purpose is to make the flow resistance small and save energy when opening the valve. At the same time, when the valve is closed, the padding between the valve shell and the valve cover and the packing around the valve stem are not subjected to force. It can prolong the service life and reduce the chance of leakage by the effect of medium pressure and temperature. In addition, it can also replace or add fillers when the valve is closed, which is convenient for maintenance.

Many people think that globe valves are low and high, but not in fact. In general, globe valves are low in and out, but there are some special cases where the cut-off valve is high and low.

1. High pressure cut-off valve with a diameter greater than 100mm

Due to the poor sealing performance of large diameter valves, the medium pressure is applied above the valve disc in order to increase the sealing of the valve in the closed state of the valve.

2. Two cut-off valves connected on a bypass pipeline, and second cut-off valves require "high in and low out".

In order to ensure the tightness of valves in a maintenance period, the valves that are often operated by opening and closing require two series cut-off valves. For bypass systems, the bypass function is as follows:

First, balance the front and rear pressure of the main valve, make the opening convenient and labor-saving, and reduce the wear of the main pipe valve.

The middle and small flow warm tubes in the start-up process;

(3) control the feed water flow on the main water supply pipe to control the boiler's boosting speed and carry out the water pressure test of the boiler. According to the flow direction of the medium, the bypass valves are the first valve and the two valve respectively. The first valve and the two valve are closed when the unit operates normally, and the two are in direct contact with the medium. In order to prevent the two valve valve housing and the valve cover between the cushion material and the valve stem around the filling of the medium and temperature for a long time, and in the process of operation can replace the valve filling, the two valve required to install the direction of "high and low".

3. Empty cut-off valve

The shut-off valve is used only in the process of boiler start up water, and the frequency of opening and closing is small, but it often causes the loss of working quality because of the tight seal. In order to improve the tightness of some enterprises, the installation direction of this kind of cut-off valve is "high and low".

4, electromagnetic fast breaking valve

The function of the electromagnetic quick break valve is to shut down quickly and cut off the fuel supply quickly. The structure of the electromagnetic fast breaking valve is similar to the structure of the cut-off valve. If the electromagnetic speed breaking valve is also the working substance from the lower part and the upper part is out, the effect of the fuel on the lower part of the valve is very large, and the weight of the electromagnetic speed breaking valve is far less than it. Therefore, if the working fluid enters the fast breaking valve from the lower part, the torque produced by the heavy hammer is less than the fuel pressure, and the fuel can not be cut off when the quick break valve moves, so it can not reach the desired purpose. If the working fluid is in the upper part of the valve, the pressure in the lower part of the valve quickly drops to zero, and the force of the fuel on the valve disc and the force of the gravity of the lever and the gravity of the lever.

In general, it is difficult to close the valve with low intake and high pressure in large and high pressure condition. If low intake and high pressure is used in high pressure and large diameter, the valve stem is easily deformed and flexed by water pressure for a long time. It can affect the safety and sealing of the valve. Users can also save a bit of cost.


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