H42F Silent Check Valve
- Spring-loaded vertical lift disc for silent, slam-free operation
- QT450-10 ductile iron body and bonnet for high structural strength
- ZG2Cr13 stainless steel disc and seat for corrosion and wear resistance
- 60Si2Mn silicon-manganese spring for reliable cyclic fatigue life
- PN16, DN40–DN400, ≤200°C, vertical installation only (flow upward)
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Product Details
The H42F-16Q silent check valve is a spring-loaded, vertical-lift check valve engineered for quiet, reliable backflow prevention in water, oil and steam pipelines. Unlike swing check valves that slam shut with an audible bang, the H42F closes smoothly under calibrated spring force the moment forward flow slows — so there is no impact, no noise, and no water-hammer pressure spike to damage pumps and pipework. Rated PN16 for DN40–DN400 and temperatures up to 200°C, it is the default choice for pump discharge, boiler feed and HVAC circulation duty.
- Spring-loaded vertical lift disc — closes without slamming, no water hammer
- QT450-10 ductile iron body & bonnet for high structural strength
- ZG2Cr13 stainless steel disc & seat — corrosion and wear resistant
- 60Si2Mn silicon-manganese spring for long cyclic fatigue life
- PN16, DN40–DN400, working temperature ≤200°C
- Vertical installation only, flow upward
H42F-16Q Silent Check Valve Overview
Model H42F-16Q | Pressure PN16 | Connection Flanged | DN Range DN40–DN400 | Type Vertical Lift, Spring-Loaded. The model code is explained letter by letter in our Valve Model Decoder.
The H42F-16Q silent check valve is a spring-loaded vertical lift check valve engineered for quiet, reliable backflow prevention in pressurized water, oil, and steam systems. Unlike conventional swing check valves that slam shut with audible impact, the H42F employs a guided vertical disc that closes smoothly against a precision-machined metal seat under calibrated spring force. The QT450-10 ductile iron body and bonnet provide exceptional structural strength, while the ZG2Cr13 stainless steel disc assembly resists corrosion and wear in demanding fluid environments. A high-quality 60Si2Mn silicon-manganese spring ensures consistent return force across thousands of operating cycles.
Core Strengths
Silent Operation
The spring returns the guided disc to the seat the instant forward flow drops, so the valve closes before reverse flow can build. No slam means no noise and no pressure spike — which is why this design is specified on pump discharge lines where water hammer is the leading cause of valve and pipe failure.
Ductile Iron QT450-10 Body
QT450-10 nodular graphite cast iron combines the castability of grey iron with tensile strength above 450 MPa and elongation of 10%, giving the body and bonnet far better resistance to pressure shock and mechanical impact than standard grey iron.
High-Strength Corrosion-Resistant Disc
The pressure plate, disc and seat are cast from ZG2Cr13 martensitic stainless steel, then machined and lapped to a sealing surface that holds up under repeated high-speed closure, resisting scoring, pitting and erosion from water, oil and steam.
Silicon-Manganese Spring
The closing spring is made from 60Si2Mn silicon-manganese spring steel, heat-treated for high elastic limit and fatigue resistance. It keeps consistent return force across tens of thousands of open/close cycles, so the valve never develops a “slow to close” failure mode.
High-Temperature Capability
The metal-to-metal seal has no rubber seat to degrade, so the H42F is rated to 200°C and is suitable for boiler feed, condensate return and district heating lines where an elastomer-seated silent valve would harden and leak.
Compact Flanged Design
Short face-to-face lengths and a slim vertical profile fit compact pump stations without custom spool pieces. Flanged ends conform to GB/T 9113 / JB/T 79 (EN 1092, ANSI B16.5 on request), drilling as standard for PN16.
Performance Specifications
| Parameter | H42F-16Q |
|---|---|
| Nominal Pressure | PN16 (1.6 MPa) |
| Working Pressure | 1.6 MPa |
| Shell Test Pressure | 2.4 MPa |
| Seal Test Pressure | 1.76 MPa |
| Working Temperature | ≤200°C |
| Suitable Media | Water, Oil Products, Steam |
| Connection Type | Flanged (GB/T 9113, JB/T 79) |
| Installation Orientation | Vertical (Flow Upward) |
| DN Range | DN40–DN400 |
Materials of Main Parts
| No. | Part Name | Material |
|---|---|---|
| 1 | Body | QT450-10 Ductile Iron |
| 2 | Bonnet | QT450-10 Ductile Iron |
| 3 | Pressure Plate / Disc / Seat | ZG2Cr13 Stainless Steel |
| 4 | Spring | 60Si2Mn Silicon-Manganese Steel |
Main Dimensions (PN16)
| DN (mm) | L Face-to-Face (mm) |
|---|---|
| 40 | 120 |
| 50 | 140 |
| 65 | 160 |
| 80 | 185 |
| 100 | 210 |
| 125 | 300 |
| 150 | 350 |
| 200 | 450 |
| 250 | 500 |
| 300 | 550 |
| 350 | 575 |
| 400 | 600 |
L = face-to-face length. Certified dimension drawings with flange drilling and approximate weights are issued with the quotation — download center or contact us for CAD files.
Structure Drawing
Design & Manufacturing Standards
- Design Standard: GB/T 12236
- Face-to-Face Dimensions: GB/T 12221
- Flange Standards: GB/T 9113, JB/T 79, HG/T 20592
- Testing & Inspection: GB/T 13927, JB/T 9092
- Ductile Iron Material: QT450-10 per GB/T 1348
- Applicable International Standards: API 6D, BS 1868 (optional)
Equivalent Models & How to Choose
Check valve model codes differ between Chinese (GB) and international conventions. The table below maps this product to the codes buyers most often search for, so you can confirm the right model in one step.
| Model Code | Also Called | Where It Applies |
|---|---|---|
| H42F-16Q | Silent check valve, non-slam check valve, spring-loaded vertical lift check valve | Vertical pump discharge lines, DN40-DN400, PN16 water / oil / steam |
| H42X / H42W | Silent check valve with rubber-seated disc (lower temperature limit) | Cold water pump stations, HVAC circulation, DN ≤200 |
| SV / RVSS type | European spring-loaded silent (non-slam) check valve | When an EN-spec substitution is required; flange faces to EN 1092 |
| H44H / H44W | Flanged swing check valve | Horizontal pipe runs where a silent type cannot be installed |
| H76H / H76W | Wafer double disc swing check valve | Space-constrained horizontal lines, DN50-DN600 |
| HH46X | Butterfly slow-closing check valve | Long pump discharge mains where water hammer must be capped at ≤1.2x |
Silent Check Valve vs Swing Check Valve
Both stop reverse flow, but they close for different reasons — and the difference decides whether your pumps and pipes survive shutdown.
| Behaviour | H42F Silent Check Valve | Swing Check Valve (H44 / H76) |
|---|---|---|
| Closing force | Spring pushes the disc back the moment forward flow drops | Disc falls by gravity after flow reverses |
| Closing speed | Near-instant; disc travels a short guided stroke | Slow; full disc swing must return |
| Water hammer | Minimal — no slam, no pressure spike on pump trip | Audible slam; spike can reach 3–8x working pressure |
| Noise at shutdown | Silent (the reason for the name) | Loud bang — often the first symptom of a failing valve |
| Low-flow behaviour | Spring preload keeps disc off the seat, no chatter | Disc flutters on and off the seat at low flow |
| Installation | Vertical pipe only, flow upward | Horizontal or rising ≤30° |
| Typical use | Pump discharge, boiler feed, HVAC circuits, fire water | Main headers, large DN, gravity lines |
Installation & Maintenance Guidelines
- Vertical installation only: install in a vertical pipeline with flow upward; horizontal installation will prevent the disc from sealing. The body flow arrow must point up.
- Pump discharge positioning: install directly at the pump outlet to protect against reverse rotation and water hammer on pump stop. Provide independent valve support for DN200 and above.
- Flow direction: the cast arrow on the body shows flow direction; reverse installation stops the disc lifting and can damage the spring.
- Flange bolting: tighten bolts in a diagonal star pattern to compress the gasket evenly; avoid over-torque on the ductile iron body.
- Spring inspection: periodically check the spring for fatigue, corrosion or loss of free length; replace it if the valve closes slowly after pump shutdown.
- Disc and seat: inspect for scoring, pitting or erosion during scheduled maintenance; minor marks can be lapped out, replace the disc if leakage exceeds acceptance criteria.
- High-temperature service: above 150°C provide pipeline expansion compensation to avoid thermal stress on the body; allow the valve to cool before disassembly.
Application Fields
The vertical, spring-loaded design makes the H42F the default choice where pumps stop and start frequently: water supply pump stations, steam boiler feed lines, hot water and chilled water circulation, condensate return, district heating networks, industrial process water, fire protection supply, and oil transfer lines. It is not suited to horizontal pipe runs or to slurries, where a swing or slow-closing check valve should be used instead.
Common installations: Water Supply Pump Stations · Steam Boiler Feed Lines · Hot Water Circulation Systems · Oil Transfer Pipelines · HVAC Heating Circuits · Industrial Process Water · Condensate Return Lines · Fire Protection Water Supply · Fuel Oil Distribution · District Heating Networks.
What We Need to Quote Your H42F Valves
- Size and quantity: DN40–DN400 and number of pieces; mixed sizes welcome.
- Pressure rating: PN10 / PN16 / PN25 (this page documents PN16).
- Fluid and temperature: water, oil or steam, and maximum operating temperature.
- Flange standard: GB/T 9113 or JB/T 79 as standard; EN 1092, ANSI B16.5, ASME on request.
- Face-to-face length: standard GB/T 12221, or your existing spacing when replacing valves.
- Documentation: EN 10204 3.1 material certificates, test records, CE or API 6D where required.
- Packaging: export plywood cases or pallets, fumigated to ISPM 15.
Send your P&ID or a pipe list and our engineers will confirm sizes, pressure class and spring specification before quoting. See our CE, API 6D and ISO certificates and the download center for datasheets and CAD drawings.
Frequently Asked Questions
Why is it called a silent check valve?
Because it closes without slamming. A 60Si2Mn spring returns a guided disc onto the metal seat as soon as forward flow slows, so there is no impact, no bang and no pressure spike. Conventional swing check valves wait for reverse flow, then drop the disc onto the seat – that is the noise you hear, and the shockwave that damages pumps.
Can the H42F be installed horizontally?
No. This is a vertical lift valve and must be installed in a vertical pipe with flow upward, so the arrow on the body points up. Horizontal fitting leaves the disc off its seat and reverse flow will not close it reliably. If your line is horizontal, use the HH46X slow-closing butterfly check valve or the H76H/H76W wafer double disc swing check valve instead.
Is the H42F-16Q suitable for steam lines?
Yes, to 200 degrees C. The ZG2Cr13 stainless disc and seat resist erosion that a rubber-seated silent valve cannot, which is why the H42F is used on boiler feed and condensate return lines. Above 150 degrees C provide expansion compensation so thermal thrust is not carried by the valve body.
What is the smallest size and the shortest face-to-face length?
The range starts at DN40 with a 120 mm face-to-face length and runs to DN400 at 600 mm, so the valve fits compact pump stations without a custom spool piece. Certified dimension drawings are issued with the quotation.
Will a spring-loaded valve cause a pressure drop?
The guided disc lifts only a short distance, so at design flow the flow path is close to that of a swing check valve of the same size. The spring preload does mean a small cracking pressure is required to open the disc; if your system runs at very low flow or very low head, tell us the duty and we will adjust the spring rate.
Do you supply test certificates and drawings?
Every valve is shell tested at 2.4 MPa and seat tested at 1.76 MPa for PN16, with records retained. EN 10204 3.1 material certificates, GA drawings with flange drilling, and CE or API 6D documentation are available on request for tender packages.
Get a Quote & Technical Support
Contact Gaoshan Valve today for dimension sheets, CAD drawings, spring specifications and customized H42F silent check valve solutions for your water, steam or oil pipeline project. Send your pipe list or P&ID for an engineered quotation.
