High pressure check valves to ISO 228, NPT and SAE J514, 1/8" to 2"

MHA states the flow direction as B to A, and the body is marked either with an arrow or with the check‑valve symbol and the ports lettered. The arrow points the way flow is allowed to pass, so it points from your pressure source towards the load. Fitted the wrong way round the valve simply blocks the line, and the symptom usually looks like a blockage somewhere else. It works equally well in a vertical or a horizontal line.

It is the pressure difference the inlet has to beat before the poppet lifts. The MHA RV is 0.5 bar as standard with a 4.5 bar option; the Inteva 504 offers seven settings from 0.34 bar (5 psi) up to 10 bar (145 psi), held to plus or minus 0.3 bar. Choose the lowest figure that reliably keeps the valve shut when you want it shut, because everything above that is pressure drop you pay for on every litre. If the valve also has to hold a small back pressure to keep another branch loaded, that is when the higher springs earn their place.

No. It is a spring inside a closed body and there is no adjuster on either make, so the setting is chosen in the part number at order. That is why we ask for it up front rather than after the valve has arrived. If a circuit turns out to need a different figure, it is a different valve, not a site adjustment.

No, and this is the commonest ordering mistake on this product. On the MHA RV the DN figure refers to the bore, not the port thread: DN20 takes a G1 or 1 inch NPT port, DN25 is 1 1/4 inch, DN30 is 1 1/2 inch and DN40 is the 2 inch. Work from the thread column in the dimensions table rather than from the DN number. Inteva sizes in millimetres of bore in the same way, so an Inteva DN25 is also the 1 inch valve.

It depends on the size and the material, not on the range. The MHA RV in steel holds 500 bar from DN6 to DN20 (1/8 inch to 1 inch), then 400 bar at DN25 and 350 bar at DN30 and DN40. The stainless RV is 350 bar at every size. The Inteva 504 is 300 bar to 1 1/2 inch and 200 bar at 2 inch. Always check the row for your own size, and remember MHA prints its own reminder to check the rating of the tube connections screwed into the valve.

On the MHA RV the stainless body is held to 350 bar across the whole range while the steel reaches 500 bar in the smaller sizes. So swapping to stainless for corrosion reasons can quietly cut your pressure margin by a third, and it is worth checking the number rather than assuming the material is a straight substitution. On the Inteva 504 the SS316 and the carbon steel bodies carry the same rating, so there is no penalty in changing material there.

Yes. Every size from 1/8 inch to 1 1/2 inch is rated 300 bar with a minimum burst of 1200 bar, and the 2 inch drops to 200 bar working with an 800 bar burst. Burst figures are tested to ISO 18869. If you need more than 200 bar at 2 inch, the MHA RV‑DN40 at 350 bar is the alternative in the same port size.

Whichever your port already is — they are not interchangeable, and forcing one into another damages both. BSPP (G, to ISO 228) is parallel and seals on a washer or an O‑ring; NPT is tapered and seals on the thread itself; SAE J514 UNF is a straight thread sealing on an O‑ring in the port face. MHA offers all three on the RV, though the SAE UNF port starts at DN8 rather than DN6. Inteva supplies BSP as standard, with NPTF on request and against a minimum quantity. If you are not certain what you have, gauge it or send us a photo with a thread gauge on it.

Both are specified for hydraulic oil — Inteva lists the 504 for oil hydraulics in fluid Group II under the pressure equipment directive, and MHA quotes its flow figures for a mineral oil of 880 kg per cubic metre. Water and water‑glycol change both the material choice (stainless rather than steel) and the seal choice, and they change the flow behaviour as well. Tell us the medium and the temperature and we will confirm whether the standard build suits it before you order.

The MHA RV is rated minus 20 to plus 100 degrees C in both steel and stainless. On the Inteva 504 the limit comes from the seal: NBR minus 30 to plus 100, Viton minus 10 to plus 200, EPDM minus 40 to plus 150 degrees C. So if you are above 100 degrees C the Inteva with Viton seals is the one to look at, and if you are well below zero the EPDM build gives the most headroom at the cold end.

Not in the standard build. Inteva makes the 504 with a metal closure and no O‑ring in the flow path, which is the main reason to choose it: there is nothing in the valve to swell, harden or extrude, and it takes pressure peaks better. Versions with O‑rings are available, in NBR, Viton or EPDM, and the seal is part of the reference number. Ask for the sealed build if tight shut‑off matters more than having no elastomer in the line.

A check valve is there to stop reverse flow, and neither maker specifies it as a zero‑leakage isolator. A metal‑to‑metal closure in particular is not a soft‑seated seal, so if your application needs a genuinely tight shut‑off, either ask for the sealed Inteva build or put a proper isolating valve in the line as well — a high pressure ball valve does that job. Tell us which of the two you actually need and we will not sell you the wrong one.

Inteva publishes the 504 as interchangeable with Gromelle 4000, DMIC CVH, Parker DC and Snap‑tite CPIFF. Send us the old part number, or a photo of the body marking, and we will come back with the 504 reference — including the opening pressure, which is the part people forget to carry across when they swap brands.

In practice, no. These are compact one‑piece bodies with no service kit, and at these pressures a reworked seat is not something to rely on. If a valve is passing, the usual cause is debris on the seat rather than wear — so it is worth flushing the line and looking through the valve before condemning it. Beyond that, replacement is the answer, and it is cheap next to the downtime.

A works certificate is available on request — ask for it with the order rather than afterwards, while the batch is still identifiable. Inteva also publishes that its burst pressures are tested to ISO 18869, and both makes stamp the body with enough information (type, size, material, batch or works order) to tie a valve in your hand back to what was supplied.