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HomeLow-pressure valvesSingle Plate Check Valve
Single Plate Check Valve
Single Plate Check Valve — 2
Single Plate Check Valve — 3
A check valve fails silently. Debris holds the disc fractionally open and the valve passes reverse flow while looking perfectly normal. Fit a Y-strainer upstream.

Why this variant

  • A wafer body — almost no length in the run, and a spring closes it, so orientation is free.
  • 2″–6″ (DN50–DN150) — check the range before you order.
  • PN16 at −20 °C to 280 °C, as published.
  • SS316 / CF8M body, Viton O-ring.
  • Flange standards: 150#, JIS 5K, JIS 10K, PN10 and PN16 — state which one.
  • Singapore & Malaysia warehouse stock — out within 24 hours.

Single Plate Check Valve

Wafer · 2″–6″ · 5 flange standards
In stockPN16SS316

A check valve using one hinged disc with a spring in 2″–6″ (DN50–DN150) with Wafer, clamped between flanges ends, a SS316 / CF8M body and Viton O-ring. It works in any orientation — a spring closes it, not gravity. Temperature −20 °C to 280 °C.

Send the size and the flange standard — quotes within 2 working hours.

TypeWafer · 2″–6″ · 5 flange standards
Size2″–6″ (DN50–DN150)
EndsWafer, clamped between flanges
BodySS316 / CF8M
SeatViton O-ring
PressurePN16
Temperature−20 °C to 280 °C
Closes onA spring — any orientation
Flange standards150#, JIS 5K, JIS 10K, PN10 and PN16
⚠ State the flange standard, not just the size. A wafer body is machined for one of them. A 4″ check valve is not one product — it is several, and they do not interchange. This is the commonest ordering mistake on wafer valves.

Construction

Single Plate Check Valve

A spring closes it, not gravity — so orientation is free.

A wafer ring with one disc in it, hinged along one side and held shut by a spring. Forward flow pushes the disc back like a door; when flow falls away the spring closes it against a seal ring set into the body face. The body is a thin ring with no bolt holes, clamped between two pipe flanges, so it takes almost no length in the run.

Against the dual plate the trade is straightforward. One disc means less metal in the bore — a hinge at one side rather than a shaft straight across the middle — so it obstructs the flow less and it is lighter and cheaper. Two discs means each travels a shorter distance, closing slightly more gently and allowing a thicker body with a higher pressure rating.

Any orientation, including flow downward

A spring closes it, not gravity — so unlike a swing check valve there are no rules about which way up it goes. Flow must still follow the arrow.

⚠ It fails silently

Debris on the seat holds the disc fractionally open and it passes reverse flow while looking normal. Fit a Y-strainer upstream, and inspect it when you get the chance.

⚠ It cannot sit at the end of a line

A wafer body is held only by the flange bolts passing either side of it. Remove one flange and nothing holds the valve.

Short is the headline

A wafer body sits between the flanges. A flanged swing check at 6″ needs 356 mm of pipe run to itself; a wafer check needs almost none.

Fit it along the arrow

Orientation stops mattering; direction never does. Fitted backwards, any check valve blocks the line.

The seat decides the fluid and the temperature

Not the body. The body is SS316; what limits it is the elastomer or the metal at the seat, and that is the thing to specify.


Photos

The stocked unit

Photographs of the stocked item, not renders.

Single Plate Check Valve — 1
Single Plate Check Valve — 2
Single Plate Check Valve — 3

Size and material are cast into the body

So the valve can be identified with no paperwork. If you need to confirm an installed unit, send us a photograph and we will read it.

We can send a marked-up photograph

If you need to identify a part before ordering spares, ask — we will number it up on a photograph of a unit in the warehouse.


Specification

Specification

Everything that goes on a purchase order.

ItemValue
Size range2″–6″ (DN50–DN150)
End typeWafer, clamped between flanges
Flange standards150#, JIS 5K, JIS 10K, PN10 and PN16
BodySS316 / CF8M
SeatViton O-ring
Working temperature−20 °C to 280 °C
Nominal pressurePN16
Strength test2.4 MPa
Seal test1.8 MPa
Air seal test
DesignASME B16.34
Face-to-faceDIN 3202
Inspection and testAPI 598
Closes onA spring — works in any orientation
Parts in the list6
StockHeld in Malaysia or Singapore

⚠ The pressure rating belongs to one standard

The nominal PN16 in the test sheet is the top of this range. A PN10 body is not a PN40 valve. Ask for the rating of the one you are ordering.

The tests are proof tests, not working pressures

The strength test proves the casting, the seal test proves the disc against its seat. Do not design to these figures.

The seat is an elastomer, and that is the temperature limit

The body is SS316 and would take far more heat. What limits it is the rubber at the seat.


Dimensions

Sizes and dimensions — as printed

6 rows. Millimetres.

On a wafer valve the body OD matters as much as the length: the body has to sit inside the flange bolt circle without fouling the bolts.

SizePart noDNØDØD1ØD2L
2″VL-S-SC-W-200-3250931093016
2½″VL-S-SC-W-200-4065113.81294017
3″VL-S-SC-W-200-48801281444617
4″VL-S-SC-W-200-64100144.51647118
5″VL-S-SC-W-200-801251909119
6″VL-S-SC-W-200-9615022611019

Letters follow the manufacturer drawing

The column headings here are the letters on the sectional drawing below. Where a letter is ambiguous we have left it as published rather than guess at it.

⚠ Take the bolt circle from the flange standard

The ØD1 column is a body diameter to check for clearance, not a bolt circle. For ANSI 150 at these sizes the bolt circles are 120.7 · 139.7 · 152.4 · 190.5 · 215.9 and 241.3 mm.

Hold the valve while you bolt up

A wafer body is centred by the flange bolts and has nothing of its own to hang on. The eye bolt on the drawing is there for exactly that.

We measure what is not published

Anything missing from this table we measure off a stocked valve, same day. Just say which dimension.


Drawing

Sectional drawing — callouts 1 to 6

Sectional drawing — Single Plate Check Valve

6 callouts, and 6 items in the parts list below — the two match one for one. The dimension letters are the column headings in the size table above: ØD the bore, ØD1 the body OD, ØD2 the disc opening and L the body thickness.

Read the drawing with the tables

Callout numbers are the item numbers in the parts list below, and the dimension letters are the column headings in the size table above.

The seat and the disc face are what wear

Everything else is a casting, the spring or a fastener. Those two surfaces take the duty every time the valve closes.

For spares, not for fabrication

This is a catalogue section, not a manufacturing drawing: no tolerances and no material callouts. Order spares by the item numbers in the parts list.


Material

Bill of material

All 6 parts, as printed.

No.Part nameMaterial
1BodyCF8M / SS316
2O-RingViton
3DiscSS316
4WasherCF8M / SS316
5BoltSS316
6Eye BoltSS316

The item numbers are the manufacturer’s

They match the callouts on the sectional drawing above, so a spares order matches the section rather than a description.

The body is SS316 / CF8M

Cast 316, which means it resists chlorides far better than 304 — and on a check valve the first thing pitting affects is the seat face, which is where it seals.

The elastomer at the seat decides the fluid

Tell us the fluid when you ask for a price; if it needs another compound, that is a specification and it has to be said before the order is placed.

Published in full, not on request

If you need to know what touches your fluid, the whole list is above.


Test pressure

Test pressure and temperature

Factory proof tests. Not a working pressure.

ItemValue
Nominal pressurePN16
Strength test2.4 MPa
Seal test1.8 MPa
Air seal test
Working temperature−20 °C to 280 °C
MediumGeneral oil, gas and water

⚠ A proof test is not a working pressure

These figures exist to prove the casting and the seal at the factory. Do not design to them.

⚠ What kills a check valve is not line pressure

It is debris on the seat holding it fractionally open. It then passes reverse flow with no sign at all. Fit a Y-strainer upstream.

The temperature belongs to the seat, not the body

The body is SS316 and would take far more heat. The figure above is the seat limit.


Choosing

Not sure this is the right one?

Body form first, then pressure, then the seat.

Choose this one when…

  • You have two flanges to clamp it between, and length in the run is tight.
  • Your size falls in 2″–6″ (DN50–DN150).
  • Pressure is within PN16 and temperature within −20 °C to 280 °C.
  • The orientation is awkward — angled, inverted or flow downward. A spring closes it.
  • Slam is a concern and a swing check closes too hard.

Choose something else when…

  • You need ANSI 300 or PN40 → the dual plate check valve. Those standards are not offered here.
  • You want the lowest pressure drop and have the length → a swing check valve. Its disc lifts clear of the bore.
  • The valve must hold pressure at the end of a line → a lugged body, which is a different product — ask us.
  • You need to isolate rather than stop reverse flow → gate valves or ball valves.
  • The fluid is dirty → still a check valve, but fit a Y-strainer upstream.

Catalogue

Official catalogue — direct download

AF Hydro Single Plate Check Valve catalogue

AF Hydro — Single Plate Check Valve

Wafer · 2″–6″ · SS316 / CF8M
PDFDownload →

FAQ

Questions we get asked

What is the Single Plate Check Valve?

A check valve in 2″–6″ (DN50–DN150) with Wafer, clamped between flanges ends, a SS316 / CF8M body and Viton O-ring. Rated PN16 at −20 °C to 280 °C. It stops reverse flow and does not isolate — there is no handle and no way to shut it from outside.

Why must I state the flange standard?

Because a wafer body is machined for one standard. This range is offered for 150#, JIS 5K, JIS 10K, PN10 and PN16 — so a 4″ check valve is really five products, and they do not interchange. This is the commonest ordering mistake on wafer valves.

Single plate or dual plate?

One disc means less metal in the bore, so the single plate is lighter, cheaper and freer-flowing. The dual plate reaches PN40 and offers ANSI 300 and PN40, which are not available here, and closes slightly more gently. If PN16 is enough, this is the better buy.

Can it be fitted vertically with flow downward?

Yes. A spring closes it, not gravity, so the valve works in any orientation — horizontal at any rotation, vertical up, vertical down. That is the main difference from a swing check valve, which cannot be used on downward flow at all. One rule still applies: flow must follow the arrow.

How do I know it is still working?

You will not know from outside, and that is the problem. A check valve fails silently: debris on the seat holds the disc fractionally open and the valve passes reverse flow while looking normal. Fit a Y-strainer upstream, and inspect it when the line is open.

What is it made of?

The body is SS316 / CF8M — cast 316, so it resists chlorides far better than 304. The seat is Viton O-ring. The full parts list is on this page, as printed in the catalogue.

What is the working temperature?

−20 °C to 280 °C, as published. That figure belongs to the seat, not the body — an SS316 body would take far more heat. If your duty is above it, the seat is what changes, and that is a specification to state before the order.

Are spares available?

What wears is the seat and the disc face; everything else is a casting, the spring or a fastener. Send the size, the seat type and the callout number and we will match it with the factory.

What are the test pressures?

The test-pressure table is on this page, as printed: nominal PN16, a strength test and a seal test. Those are proof tests, not working pressures — do not design to them.

What is your stock position for Indonesia?

We hold them in the Singapore and Malaysia warehouses, out within 24 hours of a PO. Quotes within 2 working hours.

Related: swing check valves · Y-strainers · gate valves · ball valves · our videos on YouTube.

Other check valves
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