An H44X check valve is a flanged, resilient-seated swing check valve used mainly in water supply, wastewater, irrigation, and pump discharge piping. In the model name, H commonly identifies a check valve, the two 4s indicate a flanged connection and swing action, and X indicates a resilient sealing surface. This naming convention describes a valve family. It does not make dimensions, materials, or test requirements interchangeable between manufacturers.
For buyers comparing H44X swing check valve dimensions, DN50 to DN600 states the nominal bore range only. Confirm the face-to-face length, flange drilling, body height, shaft projection, accessory envelope, maintenance clearance, and valve weight on the supplier’s general arrangement drawing before approving an order.
| Buyer question | Short answer |
|---|---|
| What does “free shaft” mean? | One shaft end projects outside the valve so a lever and weight or spring kit can be fitted. |
| Is the H44X manually operated? | No. Flow opens the disc and gravity or reverse flow closes it. External accessories modify the closing response. |
| Is H44X available from DN50 to DN600? | This is a common market range, but seat design, body pattern, shaft arrangement, and dimensions may change within the range. |
| Is a PN16 swing check valve rated for every 16 bar condition? | PN16 is a nominal pressure designation. The selected valve must also suit temperature, material, test standard, and transient pressure. |
| Can one H44X dimension table be used for every brand? | No. Use a dimension table only with its matching model, standard series, flange standard, and revision. |
What the H44X designation tells you
H44X is widely used as a Chinese valve model designation. It helps buyers identify the general construction, but it is not a substitute for a complete specification.
| Code element | Common meaning | What the purchaser still needs to confirm |
|---|---|---|
| H | Check valve or non-return valve | Product type, operating orientation, and closure behavior |
| First 4 | Flanged connection | EN, ISO, GB, ASME, or AWWA flange geometry and pressure designation |
| Second 4 | Swing type | Disc, hinge, shaft, travel, and any assisted-closing arrangement |
| X | Resilient sealing surface | EPDM, NBR, approval status, temperature range, and media compatibility |
| 16 in H44X-16 | Usually PN16 | Applicable pressure-temperature limit and required shell and seat test |
| Q in H44X-16Q | Often identifies ductile iron | Exact body grade, material certificate requirement, and coating system |
The code is the starting point for a complete order description. One example is: “H44X resilient-seated swing check valve, DN300, PN16, ductile iron body, EPDM-covered disc, EN 1092-2 PN16 flanges, specified EN 558 face-to-face series, free shaft end with lever and weight, horizontal installation, tested to the agreed valve test standard.”
For Norite’s available construction range, see the H44X swing check valve with free shaft product page.
How the swing disc and free shaft structure work
Forward flow creates enough force to lift the disc away from the seat. As pump flow falls, the disc moves back toward the seat. Gravity, reverse flow, and any fitted closing accessory determine how the last part of the stroke occurs.
The phrase “free shaft” denotes a free protruding shaft end. The external shaft end gives the project designer a place to fit one of the following:
- A lever and weight that adds adjustable closing torque
- A spring kit that assists the disc toward the closed position
- A position indicator or switch, if the valve design supports it
The valve remains flow-operated. The accessory changes the closing characteristic; it does not turn the H44X into an isolation valve or an actuated control valve.
Free shaft, closed shaft, and controlled closing
| Arrangement | External shaft end | Typical reason to choose it | Main procurement check |
|---|---|---|---|
| Free shaft H44X | Yes | Provision for lever, weight, or spring | Side clearance, shaft side, accessory setting, and guard |
| Closed-bushing swing check | No | Simple automatic service where no external accessory is required | Confirm closure is acceptable for the pump transient |
| Hydraulic slow-closing check valve | Usually part of a separate controlled design | A defined staged or delayed closure is required | Obtain the closing curve, hydraulic circuit details, and commissioning procedure |
A lever and weight does not automatically prevent water hammer. Its position and mass affect disc response, and the correct setting depends on flow deceleration after a pump trip. Where the transient is severe, compare the H44X with a micro-resistance slow-closing check valve or another non-slam design based on a surge study.
Main parts and material choices
A typical H44X resilient-seated swing check valve contains a flanged body, removable bonnet, swing disc, hinge, shaft, bushings, seals, and bonnet fasteners. Many water-service designs use a ductile iron body and a metal disc core covered with rubber.
| Part | Common option | What to check in the datasheet |
|---|---|---|
| Body and bonnet | Ductile iron | Grade, wall design, coating, flange standard, and lifting points |
| Disc | Ductile iron or steel insert with bonded rubber | Full encapsulation, edge shape, replaceability, and maximum opening angle |
| Shaft | Stainless steel | Grade, corrosion exposure, shaft diameter, and external end arrangement |
| Hinge or disc arm | Stainless steel or coated ductile iron | Size-dependent material changes and connection to the shaft |
| Bushings and O-rings | Polymer, bronze, EPDM, or NBR | Water approval, friction, wear, and replacement kit availability |
| Internal and external coating | Fusion-bonded epoxy or project coating | Surface preparation, dry film thickness, holiday testing, and repair procedure |
EPDM or NBR seat?
EPDM is commonly specified for potable water and neutral water service because of its water and temperature performance. NBR is often chosen where wastewater may contain oils or grease. Neither material should be selected from the model code alone.
Ask the supplier to confirm:
- Fluid composition and maximum operating temperature
- Chemical and oil exposure
- Drinking-water approval required by the destination market
- Rubber grade, hardness, bonding method, and batch traceability
- Storage restrictions for spare discs and sealing kits
An approval logo shown for one rubber grade or one size range does not prove that every H44X configuration has the same approval. Request the certificate scope when potable-water compliance is part of the contract.
H44X swing check valve dimensions from DN50 to DN600
The dimensions that matter extend beyond the nominal diameter. A replacement valve can have the correct DN and PN marking but still fail to fit between existing flanges, clear a wall, or leave enough room to remove the bonnet.
Dimension fields to read on the drawing
| Drawing field | What it controls | Why it matters on site |
|---|---|---|
| L or A | Face-to-face length | Determines whether the valve fits the installed spool gap |
| H or B | Body or bonnet height | Controls overhead and maintenance clearance |
| H3 or service height | Total height needed for access | Allows removal of the bonnet, hinge, and disc assembly |
| W | Body width | Affects nearby pipes, walls, cable trays, and supports |
| Shaft projection | Distance beyond the body | Required for free shaft accessories and guarding |
| Accessory envelope | Lever, weight, or spring sweep | Prevents collision during disc travel |
| D, K, n, and d | Flange outside diameter, pitch circle, hole count, and hole size | Confirms the valve will bolt to the mating flange |
| b | Flange thickness | Affects bolt length and joint assembly |
| Weight and center of gravity | Lifting and support load | Becomes a major installation issue at DN600 |
Reference H44X dimensions
The table below reproduces one published PN16 H44X pattern as a quote-stage reference only. The A and B values belong to that drawing series. They are not universal Norite production dimensions and must not be copied into a purchase order without the matching drawing.
| Nominal size | Inch reference | A, face-to-face reference (mm) | B, drawing height reference (mm) |
|---|---|---|---|
| DN50 | 2 | 203 | 86 |
| DN65 | 2 1/2 | 216 | 100 |
| DN80 | 3 | 241 | 110 |
| DN100 | 4 | 292 | 120 |
| DN125 | 5 | 330 | 140 |
| DN150 | 6 | 356 | 150 |
| DN200 | 8 | 495 | 180 |
| DN250 | 10 | 622 | 251 |
| DN300 | 12 | 698 | 310 |
| DN350 | 14 | 787 | 350 |
| DN400 | 16 | 914 | 380 |
| DN450 | 18 | 978 | 400 |
| DN500 | 20 | 978 | 450 |
| DN600 | 24 | 1295 | 520 |
Published catalogs for other resilient-seated swing check valves show different values. For example, an EN 558 Basic Series 48 valve may list a 200 mm face-to-face length at DN50 and 699 mm at DN300, while a larger DN350-DN600 product family may use 800 mm at DN350 and 1300 mm at DN600. The model-specific GA drawing controls the order.
DN50 check valve versus DN600 check valve
The same model name covers very different installation work at the ends of the range.
| Project issue | DN50 check valve | DN600 check valve |
|---|---|---|
| Handling | Often manageable with standard workshop lifting practice | Requires a lifting plan, verified lugs, center-of-gravity data, and substantial access |
| Pipe support | Local piping loads still need control | Valve mass and lever loads can require dedicated structural support |
| Disc dynamics | Lower disc mass, but flutter can still occur at low or unstable flow | Higher disc inertia and a larger system consequence if closure is poorly controlled |
| Accessory clearance | Small lever or spring envelope | Large side envelope and guarded moving parts may govern room layout |
| Replacement fit | Confirm L, flange drilling, and bonnet access | Confirm L, flange drilling, W, H3, weight, lifting route, and dismantling space |
| Hydraulic review | Check pressure loss and stable opening at actual duty | Use pump and system transient data; DN alone cannot predict surge behavior |
For a DN600 check valve, ask for the GA drawing and accessory assembly drawing before the pump room layout is frozen. A dimension table without the lever position, service clearance, and weight is incomplete.
What PN16 means for an H44X check valve
PN16 is a nominal pressure designation associated with a standardized component system. It is not a promise that every valve marked PN16 can operate at exactly 16 bar under every temperature, material, and surge condition.
Check four pressures separately:
- Normal operating pressure at the valve location
- Maximum static pressure, including tank level and elevation head
- Transient pressure during pump start, trip, and valve closure
- Factory shell and seat test pressure under the specified test standard
The mating flanges must use the same dimensional system. An EN 1092-2 PN16 flange and an ASME Class 125 flange should not be treated as interchangeable because the nominal size looks similar. Confirm the outside diameter, bolt circle, hole count, hole diameter, facing, gasket, and fastener specification.
For a broader explanation of pressure designations, see PN10 vs PN16 vs PN25 valves.
Which standards belong in the specification?
A useful valve specification assigns one job to each standard. A list of standard numbers without their scope can mix incompatible dimensional systems.
| Specification item | Common standard route | What the standard is used to define |
|---|---|---|
| Water-supply check valve performance | EN 1074-3 | Fitness-for-purpose requirements and verification for check valves in water systems |
| Metallic check valve product requirements | EN 16767 or the project-specified product standard | Design and performance requirements for metallic check valves |
| Face-to-face dimension | EN 558 selected basic series, ISO 5752, or GB/T 12221 | Installed length and dimensional interchangeability |
| Cast iron PN flange | EN 1092-2, ISO 7005-2, or GB/T 17241.6 | Flange dimensions and drilling |
| Pressure and closure test | EN 12266-1 or ISO 5208, as invoked by the product specification | Shell integrity and seat tightness test method |
| American waterworks swing check valve | AWWA C508 with the specified American flange and dimension standards | Requirements for iron-body swing check valves in waterworks service |
| Potable-water contact | Destination-market approval and project specification | Acceptance of coatings, rubber, and other wetted materials |
Do not write “EN/AWWA standard” as if it were one configuration. A PN16 swing check valve with EN flanges and an AWWA-pattern check valve may differ in face-to-face length, flange drilling, pressure basis, materials, and test requirements. Name the complete route in the RFQ.
Standards also change. State the required edition in the purchase specification, or require the supplier to identify the edition used in its offer.
Where H44X fits in a pump station
An H44X is commonly installed on a pump discharge line to stop reverse flow after the pump shuts down. The full waterway and resilient disc can suit clean water, screened wastewater, reclaimed water, irrigation, and circulation systems where low head loss and top access are useful.
It is a reasonable candidate when:
- The medium is compatible with the body coating and rubber seat
- Actual flow can open the disc fully and hold it stable
- The line orientation is approved by the manufacturer
- The pump room has enough space for the body, bonnet, free shaft accessory, and maintenance work
- A hydraulic review shows that the proposed closing arrangement is acceptable
Do not select it from pipe size alone. Frequent pump cycling, low velocity, strongly varying flow, long rising mains, high static head, or a rapid power-failure transient can make disc flutter or slam more likely. Wastewater containing rags, fibers, or large solids may also require a different check valve construction.
The detailed hydraulic comparison belongs in a separate selection guide. Use Check Valve for Pump Stations to compare closing response and surge risk, and Swing Check Valve vs Wafer Check Valve when installation length and valve type are still open.
Pump station data needed before selection
Ask the designer or operator for:
- Minimum, normal, and maximum flow through each valve
- Pump curve, operating point, and number of pumps running in parallel
- Static head and pipeline profile
- Normal pressure and maximum allowable transient pressure
- Pump start, controlled stop, and power-failure sequence
- Pipe material, diameter, length, and wave speed used in the surge model
- Required valve closing characteristic or permitted reverse velocity
Request the manufacturer’s head-loss curve for the exact size and configuration. A “full bore” description does not quantify pressure loss or prove that the disc will remain fully open at minimum flow.
Installation checks for horizontal and vertical piping
Follow the arrow cast or marked on the body. For a conventional swing check valve in a horizontal line, keep the hinge shaft in the approved horizontal position so the disc can move and return correctly.
Vertical installation may be allowed only with upward flow and with written manufacturer approval for the exact model and accessory arrangement. Do not install a gravity-dependent swing check valve in a vertical downflow line unless the manufacturer has designed and approved it for that duty.
Before installation:
- Compare the valve tag and signed drawing with the line list.
- Check flange drilling, face-to-face length, gasket, bolts, and pipe alignment.
- Inspect the bore and disc area for packing material, coating damage, and debris.
- Provide independent pipe support so the valve is not used to pull misaligned flanges together.
- Leave room above the bonnet and around the lever, weight, spring, guard, drain, and lifting points.
- Confirm that nearby elbows, reducers, pumps, and control valves will not create unstable flow at the disc. Follow the approved manufacturer layout rather than applying an arbitrary straight-run rule.
- Flush the line under a controlled procedure and verify free disc movement before full service.
On many pump discharges, the check valve is followed by an isolation valve so the check valve can be maintained without draining the downstream main. The final sequence, spacing, dismantling joint, and support arrangement must follow the project piping design.
H44X RFQ checklist for buyers
| Information to send | Why Norite needs it |
|---|---|
| Quantity and DN for each line | Defines the size schedule and production scope |
| Required pressure designation | Starts the body and flange selection |
| Fluid and solids description | Guides rubber, coating, disc, and bore selection |
| Operating and design temperature | Checks elastomer and coating limits |
| Normal, minimum, and maximum flow | Supports disc stability and head-loss review |
| Normal, static, and surge pressure | Prevents selection from steady pressure alone |
| Flange standard, facing, and drilling | Prevents an incompatible pipe connection |
| Required face-to-face standard and series | Controls replacement fit and spool length |
| Installation orientation and flow direction | Confirms gravity and accessory arrangement |
| Available L, H, W, H3, and side clearance | Confirms room for the valve and maintenance |
| Free shaft side and accessory | Defines lever, weight, spring, guard, or switch arrangement |
| Body, shaft, disc, and rubber materials | Establishes the bill of materials |
| Coating and potable-water approval | Defines wetted-material compliance and documentation |
| Test standard and acceptance class | Defines shell and seat test requirements |
| Documents required with the offer | Avoids late requests for drawings, curves, and certificates |
The supplier’s offer should state every deviation. “Comply” is not enough when the RFQ contains more than one possible face-to-face series or flange system.
Drawing, inspection, and factory test documents
Before production, review a GA drawing that shows:
- Face-to-face length and all flange details
- Body height, width, shaft projection, and accessory envelope
- Maintenance and disc-removal clearance
- Valve weight, center of gravity, and lifting points
- Flow arrow and approved installation orientation
- Material list and coating specification
The inspection and test plan should identify the applicable standard, hold or witness points, gauges, test duration, test pressure, permitted leakage, and report format. Depending on the contract, the final document package may include material certificates, rubber and coating certificates, pressure test reports, coating inspection records, dimensional inspection, marking photographs, and packing details.
For DN600, review the shipping split, lifting method, flange protection, lever restraint, and site assembly instructions before dispatch. Large-valve handling should not rely on the shaft, lever, or hand-built lifting points.
Frequently asked questions
What is a free shaft H44X check valve?
It is a swing check valve with an external shaft end available for a lever and weight or spring. The disc still opens and closes automatically in response to flow.
Are H44X dimensions standardized?
Only when the exact model invokes a named face-to-face series and flange standard. The H44X code by itself does not define L, H, flange drilling, shaft projection, weight, or accessory clearance.
What are typical H44X swing check valve dimensions for DN50 and DN600?
One published PN16 schedule lists A as 203 mm at DN50 and 1295 mm at DN600, with corresponding B values of 86 mm and 520 mm. Other product families use different values. Treat these as reference figures and order from the supplier’s signed drawing.
Can a PN16 H44X be installed vertically?
Some designs permit vertical installation with upward flow. Approval depends on the exact disc, shaft, and accessory arrangement. Vertical downflow is generally unsuitable for a gravity-closing swing check unless the design is specifically approved for it.
Does a lever and weight prevent water hammer?
It can change closing torque and timing, but it cannot guarantee a safe transient. Pump trip behavior, reverse velocity, static head, pipeline length, and the accessory setting all affect the result.
Is EPDM suitable for wastewater?
It can be suitable for many water and wastewater duties, but oils, chemicals, temperature, and regulatory requirements must be checked. NBR may be preferred where oil or grease exposure is significant.
Can H44X handle sludge and fibrous sewage?
Suitability depends on solids size, concentration, ragging risk, velocity, and the internal flow path. For difficult sludge service, compare other options in the sludge valve selection guide rather than assuming every swing check valve is non-clogging.
Specify the drawing before placing the order
Start the enquiry with the DN, PN, fluid, temperature, flange standard, face-to-face series, installation orientation, pump duty, surge data, seat material, and free shaft accessory. Norite can then prepare the matching technical offer, dimension drawing, head-loss information, and inspection document list.
Contact Norite with the line list and pump data to review an H44X configuration from DN50 to DN600.
