Selection of the outlet stop valve for the valve

H41 is a flanged, straight-through lift-type check valve; H42 is a flanged, vertical lift-type check valve; H44 is a flanged, single-disc swing-type check valve. Generally, check valves are installed between the pump and the valve.

I support the view from the second floor. Additionally, you can search for valve selection manuals, which contain more comprehensive information; they are available on this forum: http://bbs.hcbbs.com/viewthread.php?tid=6776&highlight=%B7%A7%C3%C5%D1%A1%D3%C3%CA%D6%B2%E1

In accordance with the \"Method for Compiling Valve Models,\" a valve model consists of seven units: a hyphen is used to connect the fifth and sixth units. The first unit is the type code, represented by Chinese Pinyin letters: Type Code Type Code Gate Valve Z Plug Valve X Globe Valve J Check Valve and Foot Valve H Throttle Valve L Safety Valve A Ball Valve Q Pressure Reducing Valve Y Disc Valve D Trap Valve S Diaphragm Valve G For valves designed for temperatures below -40°C, insulated valves with heating jackets, and valves equipped with bellows (instead of packing boxes), the Chinese Pinyin letters “D”, “B”, and “W” are added in front of the type code respectively. Unit 2 is the transmission method code, expressed in Arabic numerals: Transmission Method Code Transmission Method Code Solenoid valve 0 Bevel gear 5 Electro-hydraulic 1 Pneumatic 6 Electro-hydraulic 2 Hydraulic 7 Worm gear 3 Pneumo-hydraulic 8 Spur gear 4 Electric 9 For valves driven by handwheels, handles, or wrenches, as well as all safety valves, pressure relief valves, and steam traps, this code is omitted. Certain pneumatic or hydraulic valves come in two types: normally open and normally closed. Those that are normally open are denoted by 6K and 7K, while those that are normally closed are denoted by 6B and 7B. Valves that are both pneumatic and manual are denoted by 6S. Explosion-proof electric, denoted by 9B. Unit 3 is the connection type code, expressed in Arabic numerals: Connection Type Code Connection Type Code Internal thread 1 Clamp-type 7 External thread 2 Clamp 8 Flange 4 Collar 9 Welding 6 Unit 4 is the structural type code, also expressed in Arabic numerals: Gate Valve Structural Type Code Stem-type Wedge-type Elastic gate 0 Rigid Single gate 1 Double gates 2 Parallel single gate 3 Double gates 4 Stemless wedge-type single gate 5 Double gates 6 Structure type codes for stop valves and throttle valves Straight-through type 1 Angle type 4 Straight-flow type 5 Balanced straight-through type 6 Angle type 7 Structure type codes for ball valves Floating straight-through type 1 L-type Three-way type 4 T-type 5 Fixed straight-through type 7 Structure type codes for disc valves Lever type 0 Vertical plate type 1 Inclined plate type 3 Structure type codes for diaphragm valves Ridge type 1 Cut-off type 3 Gate type 7 Structure type codes for plug valves Packing straight-through type 3 T-type three-way type 4 Four-way type 5 Oil seal straight-through type 7 T-type three-way type 8 Structure type codes for check valves and foot valves Rising straight-through type 1 Vertical type 2 Swing single-disc type 4 Multi-disc type 5 Double-disc type 6 Structure type codes for safety valves Spring-loaded Closed with fins Fully open type 0 1 2 With wrench Fully open type 3 Dual-spring slightly open type 4 Slightly open type 5 Unsealed Fully open type 6 Slightly open type 7 With control mechanism Fully open type 8 Pulsating type 9 Lever-type safety valves; the letter “G” (from Chinese pinyin) is added before the type code. No numerical code is specified in the new standard. The old standard uses 1 to represent single-rope slightly open type, 2 for single-rope fully open type, 3 for double-rope slightly open type, 4 for double-rope fully open type, and 6 for pulse type. Valve pressure relief valve structure code: Diaphragm type – 1; Spring-diaphragm type – 2; Piston type – 3; Bellows type – 4; Lever type – 5. Drain valve structure code: Float type – 1; Bell-shaped float type – 5; Pulsating type – 8; Thermodynamic type – 9. The fifth category consists of codes for the valve seat sealing surface or lining material, represented by Chinese pinyin letters: Valve seat sealing surface or lining material code: Copper alloy – T; Rubber – X; Nylon – N; Fluoroplastic – F; Tin-based bearing alloy (Babbitt) – B; Alloy steel – H; Nitrided steel – D; Cemented carbide – Y; Lined rubber – J; Lined lead – Q; Enameled ceramic – C; Boronized steel – P. When the sealing surface is machined directly on the valve body, it is denoted by W. After the crossbar is the sixth unit, which indicates the nominal pressure value. The so-called nominal pressure refers to the pressure that a valve is nominally capable of withstanding. In fact, its pressure resistance should be higher, but for safety reasons, it is kept within the nominal pressure when in use. The pressure unit is kg/cm2, but when indicating the model, only the pressure value is written. According to the JB74－59 standard, the nominal pressure values are as follows: 1, 1.5, 4, 6, 10, 16, 25, 40, 64, 100, 200, 250, 320, 400, 500, 640, 800, 1000. No provisions are made for over 1000. Finally, in Unit 7, the valve body material is indicated using Chinese pinyin letters: Valve body material Code Gray cast iron Z Malleable cast iron K Ductile iron Q Carbon steel C Cr5Mo steel I 1Cr18Ni9Ti steel P Cr18Ni12Mo2Ti steel R 12Cr1MoV steel V. However, for gray cast iron valves with a nominal pressure of kg/cm2 and carbon steel valves with the same nominal pressure, this code can be omitted.

The H44 single-disc swing check valve is installed on vertical pipes; it is compared to the H42, which is a vertically mounted check valve with flange connections – which one is better?

For these two projects of mine, I chose the H44 model, and it seems to work fine. A check valve is connected first at the pump outlet, followed by another valve, with a short section inserted in between