General specification for slow closing check valve

2022-08-06
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General technical conditions for slow closing check valves for drainage

the relevant contents of the standard are introduced as follows:

the standard is applicable to the nominal pressure PN4.0MPa, nominal diameter DN? 4000mm, the working temperature is not greater than 80 ℃, and the working medium is the flange connected slow closing check valve of drinking water, raw water, industrial circulating water, seawater, sewage and other non corrosive media. The technical requirements in the standard are as follows:

1 the structural length of the flange connected slow closing check valve shall comply with the provisions of gb/t12221 or as agreed by the user. When the butterfly check valve is opened, the extension length of the butterfly plate shall not affect the use

2 flange connection dimension and sealing surface type shall comply with the provisions of gb/t17241.6, gb/t17241.7 or gb/t9112

31 keep the experimental machine clean; The minimum wall thickness of valve body shall comply with gb/t12236, gb/t12238 or gb/t13932 standards

4 materials

4.1 the materials of main parts such as valve body, bonnet, disc (butterfly plate) and valve shaft of slow closing check valve shall comply with the provisions of gb/t12236, gb/t12238 or gb/t13932 on petrochemical products closely related to oil price

4.2 the material of damping piston cylinder of slow closing device shall meet the requirements of system pressure, the surface of piston and piston rod shall be plated with hard chromium, and the sealing ring of piston and piston rod shall be made of oil resistant materials such as laminated rubber

4.3 the anti-corrosion coating and rubber seal used for the inner cavity of slow closing check valve body for water supply and other metal parts in contact with water shall be non-toxic and odorless

5 the closing process of slow closing check valve shall be divided into two stages: quick closing and slow closing, and the slow closing time shall be adjustable

6 the slow closing opening of the check valve disc of the slow closing check valve, i.e. the extension length of the slow closing piston, shall be adjustable in the whole process

7 the check valve disc (butterfly plate) of the slow closing check valve shall be opened and closed flexibly without jamming

8 the damping piston in the slow closing device must be sensitive. When the upper check valve disc (butterfly plate) is opened, it can automatically and quickly extend 6 papers published in core journals at home and abroad to the predetermined working position. When the upper check valve disc (butterfly plate) is closed to the slow closing position, it can play an effective slow closing role. The capacity of the damping piston cylinder in the slow closing device shall be matched with the regulating valve used to avoid excessive force of the damping piston cylinder and pipeline, so as to achieve the purpose of adjustable hammer elimination

9 the slow closing device of external damping slow closing check valve and hydraulic butterfly check valve shall be attached with a mechanism to monitor the liquid level of damping medium

10 the self damping slow closing check valve does not allow raw water and sewage with solid particles to enter the slow closing device directly to avoid blocking or damaging the seals

11 the hydraulic control butterfly check valve and butterfly slow closing check valve shall be equipped with an indicator that correctly displays the opening position of the butterfly plate. Therefore, we have obtained ISO9001 international quality system certification and national measurement system certification

12 the hydraulic control butterfly check valve shall be equipped with a heavy hammer or an accumulator as an additional force source to automatically close the valve in case of power failure

13 the relevant connection, transmission and support parts of the slow closing device shall have sufficient strength and rigidity

14 hydraulic device: standard hydraulic parts and electrical components shall be products with reliable quality, good performance and long service life, and shall be tested according to the provisions of relevant standards. They can be used only after passing the test. After the hydraulic device is assembled, various parameter performance tests and adjustments shall be carried out to make it meet the design requirements of "slow closing" of the valve

15 the external paint layer and color of the slow closing check valve shall be uniform, and the surface shall be smooth and flat without defects such as scars, sagging, blistering and obvious cracks

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