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Right, so non return valves. We get asked about these constantly – literally had three calls about them just this morning before I’d even finished my coffee. And you know what? Every single customer thinks they need the same thing, but they really don’t.
Here’s the thing that trips people up…
Look, I’m not going to bore you with textbook definitions. A hydraulic non return valve (some people call them check valves, same thing really) basically lets fluid go one way and stops it going backwards. That’s it. Simple concept, right?
Wrong. Because the devil’s in the details.
We’ve been selling these for nearly 15 years now, and I’ve seen people spec completely the wrong valve for their application more times than I can count. Last month we had a customer in Sheffield who’d bought three different valves from another supplier – all wrong. Cost them about £800 and two weeks of downtime. Could’ve just rung us first, but there you go.
This is where it gets interesting. Every non return valve has what’s called a cracking pressure – that’s the minimum pressure needed to open it. And this is where people mess up spectacularly.
I had a bloke from a food processing plant in Norwich ring me in 2022 (might’ve been early 2023, can’t remember exactly). His system kept losing pressure overnight. Turned out he’d installed a valve with too high a cracking pressure. The pump couldn’t generate enough force on startup. Classic mistake.
See, if you’re running:
But don’t just copy these numbers. Your application might be totally different.
I’m going to be honest with you – sometimes you don’t even need one. Yeah, I know, we sell them, but I’d rather tell you the truth than have you waste money.
Mobile equipment – like excavators, cranes, that sort of thing. You absolutely need them here. When the machine’s parked up overnight, you don’t want cylinders drifting. We supply loads of these to construction companies across the Midlands. Parker do some decent ones, Bosch Rexroth too, though their lead times have been terrible lately (8 weeks last I checked, might be better now).
Vertical actuators – anything fighting gravity needs a non return valve. Had a customer last year with a scissor lift platform. Didn’t have proper check valves. You can imagine what happened. Nobody got hurt thank God, but the HSE weren’t happy.
Jack applications – crucial here. We work with a lot of workshops and recovery services. These guys know their stuff, but occasionally we get someone new to the industry who doesn’t realize how important the valve spec is.
Horizontal cylinders in low-speed applications? Probably fine without. Closed-loop systems? Already got protection built in usually. Some engineers way over-spec these systems – seen quotes with like six non return valves where two would do the job.
Alright, this is where I lose some people, but stick with me.
Spring loaded non return valves – these are your basic ones. Spring keeps it shut, pressure opens it. Simple. Reliable. Bit noisy sometimes though. We sell tons of Hydrotech and HydraForce spring types. They’re workhorses.
Pilot operated ones – now these are clever. They use system pressure to help control opening and closing. More precise, better for complex systems, and definitely quieter. But more expensive, obviously. And more things to go wrong if I’m being brutally honest.
I remember – must’ve been 2019 or so – we had this big job for a marine application. Customer wanted pilot operated because of the noise thing (fair enough, it was for a luxury yacht). But the system ran intermittently. Pilot operated valves didn’t like that. Ended up switching to spring loaded with better mounting to reduce noise. Worked out cheaper too.
This genuinely drives me mad. People look at the pressure rating and think they’re done. Then wonder why their cylinder moves like it’s wading through treacle.
Flow rate matters! Actually, sometimes it matters MORE than pressure rating.
If you’re pushing 60 litres per minute through a valve rated for 40, you’re going to get:
We did some testing with our tech team last year (shoutout to Dave and Piotr, they did all the hard work). A 1/2″ valve at 50 LPM was showing 8 bar pressure drop. Same valve at 30 LPM? Only 2.5 bar. Huge difference.
Most valves are steel. Standard. Fine for 90% of applications.
But…
If you’re dealing with:
Had a customer in the fish processing industry (can’t remember the company name, somewhere in Scotland I think). They were getting about 6 months out of standard steel valves. Switched to 316 stainless, problem solved. Cost more upfront but paid for itself in a year.
Vertical, horizontal, upside down – normally doesn’t matter with modern valves. BUT (big but here), some older designs or cheaper ones can be position-sensitive.
We always say: if the data sheet doesn’t specifically say “any position,” mount it with the inlet at the bottom. Just to be safe. Gravity’s your friend.
Oh, and cartridge vs in-line? That’s a whole other discussion. Cartridge types are great if you’ve got a manifold system. In-line if you’re retrofitting or doing mobile equipment. We keep both in stock usually, though stock levels have been all over the place since Brexit if I’m honest.
This one’s technical but important. When fluid slams to a stop in your system, you get pressure spikes. Sometimes 2x or 3x your normal operating pressure. For maybe 100 milliseconds. But that’s enough to kill a valve over time.
If you’re getting repeated failures every 6-12 months, this is probably why. Solutions:
We worked with a waste management company – think it was 2021, maybe early 2022 – they were replacing valves every 8 months like clockwork. Turns out their cylinder speeds were way too fast for the valve spec. Added some flow controls, problem disappeared. They were skeptical at first but yeah, sorted.
Being independent means we’re not tied to one manufacturer. Which is brilliant, but also means our stock is a bit… eclectic.
We always have:
Special stuff like pilot operated, stainless, or really high flow? We can get it, but you’re looking at 2-6 weeks usually. Sometimes longer if it’s coming from Germany or the States.
Proper good: Bosch Rexroth, Parker, Sun Hydraulics (expensive but brilliant), HydraForce
Decent: Eaton, Danfoss, Casappa
Fine for the price: Hydro Leduc, some of the Italian brands
Avoid: Not naming names, but if it’s £12 on eBay and claims to be rated for 350 bar, it’s probably rubbish
Standard cartridge valve? £25-60 usually. Inline type? £40-120. Pilot operated? £150-400 depending on size and spec.
Stainless adds about 40-60% to the cost. Custom seals add maybe £20-30.
We’re not the cheapest. Never claim to be. But we’re definitely not the most expensive either, and our stuff actually works. Plus, if you ring us with a problem, you get someone who knows what they’re talking about, not a call centre in who-knows-where.
“Can I use this horizontally even though the drawing shows it vertical?”
Usually yes, but check the data sheet. If it doesn’t say, ring us.
“Mine’s leaking backwards, is it knackered?”
Maybe. Check if there’s dirt on the seat first. Sometimes you can clean them. Sometimes they’re toast.
“What’s the difference between a check valve and a non return valve?”
Nothing. Same thing. Like how some people say hydraulic and some say pneumatic… wait no, that’s different. Bad example.
“Do I need one in my pressure line?”
Probably not. Return line or actuator, yes. Pressure line, usually there’s already enough going on.
“Your competitor quoted me £40 less.”
Cool. Buy from them then. But when it leaks in three months, we’ll still be here.
When you ring us (or anyone really), have this info ready:
Honestly, if you’ve got those six things, we can sort you out in ten minutes. If you don’t have them, we’ll help figure it out, but it takes longer.
Non return valves are pretty low maintenance. Unless they’re not.
Check them annually if they’re critical. Six monthly if they’re supporting loads. Look for:
Replace them if they’re leaking significantly. You can’t really rebuild most modern ones – they’re too cheap to make it worthwhile. Exception: really expensive pilot operated ones, sometimes worth rebuilding.
Look, non return valves aren’t complicated. But specifying the right one for YOUR application takes actual thought. Don’t just grab whatever’s cheapest or what worked on your last job.
Different systems, different needs. A valve that’s perfect for a static machine tool application will be completely wrong for mobile equipment. Pressure ratings matter, but so do flow rates, cracking pressures, and about five other things.
Ring us if you’re not sure. Seriously. We’d rather spend 15 minutes on the phone helping you get it right than deal with returns and complaints later. Plus we’re pretty friendly, even Dave, and he’s Northern.
“A leader in hydraulic technology, A convenient choice around you”
