The knowledge for water treatment control valves' maintenance and pressure testing

How to maintain the water treatment control valves?

1. Firstly, close the front and back sides of the water treatment control valves.

2. Loose the screw which on the bonnet of water control valves, so release the valves’ pressure.

3. Pick out all of the screws, including the copper pipe’s nut in the control pipeline.

4. Pick out the bonnet and spring.

5. Pick out the axis, diaphragm and piston, pay attention to not damage the diaphragm.

Water treatment control valve is used to control water pressure, is composed of a main valve and its attached conduit, guide valve, needle valve, ball valve and pressure gauge and etc. According to the purpose of use, function and different places, it can be evolved into remote control floating ball valve, pressure reducing regulator valve, slow-closing check valve, flow control valve, balanced pressure relief valve, hydraulic electric control valve, water pump control valve and etc. In order to match the requirement of facilitating sewage, should install the filter in front of the water treatment control valves. Such kind valves should be installed horizontally in the pipeline.

The pressure testing for water treatment control valves:

A. The test pressure of strength should be 1.5 times of nominal pressure;

B. The test pressure of tightness should be 1.5 times of nominal pressure;

C. The test pressure should keep same during the testing duration, the shell packing and valve disc sealing surface should also have no leakage on this time.

D. The testing duration of valve can refer as above table.

The water conservancy valve is one kind of liquid level automatic control valve, controls the main valves’ opening and closing by controlling the loop float ball valves’ opening and closing, so that can set the liquid level’s control. The remote control float assembly should be consist of the below components (along the flow direction):

A. Control valve (rising and non rising gate valve or butterfly valve); B. Filter; C. Remote control float ball valve

A: If the medium is clean, the pipe filter can be instead by microfilter in the main valve conduit system.

B: There should have space to remove the filter on the installation site.

When the inlet pipe's nominal diameter of pool(box) which used in life, production and fire water supply system is larger than or equal to 50mm, it better to set up the remote control float ball valve. The nominal diameter of the remote control float ball valve should be same as the nominal diameter of the pipeline. Filter should be set before the remote control float ball valve and below requirement should be matched:

A: The material for net should have enough strength and stiffness, it is better to be made by stainless steel and copper. The mesh orifice’s total water flow area should be 1.5-2 times of the pipe sectional area, and the holes number should be 20-60 mesh.

B. should be easy to clean up.

Remote control float ball valve should be installed in pool or water tank inlet pipe, should be installed horizontally, valve cover up.  The control tube and float ball shall meet the following requirements:

A. The remote control float ball valve's tube should be fully fixed on the pool or water tank, the total length should be more than 8cm, the float ball center should be 1cm away from the water inlet, or the water inlet pipe should adopt wave elimination device

B. The part above overflow water level in the same pool or water tank should have a vent hole to prevent backflow pollution from destroying siphon phenomenon, with an aperture of 10mm, and the center of the hole and the height of overflow water level should meet the requirements.

Life water supply system adjustable pressure reducing valve, valve before and after the maximum pressure difference is not greater than 0.4mpa;  In places with quiet requirements (residential, hotel, hospital) life water supply system adjustable pressure reducing valve before and after the maximum pressure difference should not be greater than 0.3mpa.  When the maximum pressure difference between the adjustable pressure reducing valve before and after the domestic water supply system exceeds the above provisions, the adjustable pressure reducing valve should be set in series or take anti-noise measures

When the nominal diameter of the adjustable pressure reducing valve is not larger than 50mm, the linear pressure reducing valve should be used;   When larger than 50mm less than 100mm, the pilot pressure reducing valve should be used.

For some high-rise civil buildings with uneven water consumption (such as hotels, residences and hospitals), where there is a quiet requirement, the adjustable pressure reducing valve should be set in parallel with diameter reduction.  The setting of reducing parallel connection shall meet the following requirements

A. Determine the diameter of the primary and secondary pressure reducing valves according to their working conditions and flow characteristics.  General auxiliary pressure reducing valve should be two or more than two steps smaller than the nominal diameter of the main pressure reducing valve;

B. The post-pressure of the auxiliary pressure reducing valve should be 00.020~ 0.035mpa (dynamic pressure value) higher than that of the main pressure reducing valve.

Note: A. When reducing diameter and parallel connection is set, the design flow through shall be calculated according to the simultaneous operation of pressure reducing valves with different nominal diameters or adjustable types.

B, reducing parallel setting is only applicable to adjustable pressure reducing valves.

C. When the main pressure reducing valve is a direct pressure reducing valve, the auxiliary pressure reducing valve can not be connected in parallel.

D. When reducing in parallel setting, the main reducing valve may not be combined with the reducing valve

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