Guide · Couplers, adapters and swivels
Live swivels and swivel fittings: what their ratings cover
A live swivel turns under pressure and has its own PSI, temperature and rotation limits; a swivel nut turns only while you connect. How to read both ends and the rating.
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Short answer
A live swivel rotates while the line is under pressure, and it has its own pressure, temperature and rotation limits. A swivel nut only turns while you connect it. For either, check the thread on both ends and the rating, and keep the rating at or above your machine's output.
Live swivel or swivel nut
A live swivel is a rotating joint built to turn in use, under pressure, so the hose does not twist as you move the gun. It has bearings and seals for that job, and the maker rates it for pressure, temperature and speed.
A swivel nut is the loose collar on many hose ends and adapters. It spins so you can thread the fitting on without turning the hose. Once tight, it does not rotate in use.
The two look alike in listings, because both use the word "swivel". The rating tells them apart: a live swivel states how it may rotate under pressure; a swivel nut does not.
Live swivels built into guns
Some guns include a live swivel at the inlet.
- The MTM Hydro SGS28 gun has a 3/8 in FPT inlet with an integrated stainless steel live swivel and a 1/4 in FPT outlet.[1] These are pipe-thread ports, not M22, so a consumer M22 hose needs suitable fittings to connect.
- McKillans lists its swivel gun at a maximum recommended 3,000 PSI and 2.6 GPM, with a 3/8 in male inlet and a 1/4 in female quick-connect outlet.[2] McKillans' page shows no temperature rating.
If your gun already has a swivel, you may not need another one in the line. See replacement trigger guns for the gun-side connections.
An inline example: Mosmatic DGV 32.557
Inline live swivels sit between the hose and the gun. The figures below come from a retailer listing, not from Mosmatic: we could not read Mosmatic's own catalog or specifications. They apply to variant 32.557 only; other DGV variants have different threads.
- A retailer lists the DGV 32.557 at a maximum of 4,000 psi, 250°F and 30 rpm, with 1/4 in NPTF threads on both ends.[3]
- The same listing says it uses one thrust ball bearing and is rated for media with pH 3 to 12, filtered to 10 microns, or compressed air up to 290 psi.[3]
- It gives a weight of 6.5 oz and an overall length of 2.72 in.[3]
- It describes the swivel as built for live rotation under full pressure, with a brass nickel-plated body, a stainless steel inner part and an NBR O-ring seal, with EPDM or FKM optional.[3]
| Spec (retailer's listing, DGV 32.557) | Value |
|---|---|
| Maximum pressure | 4,000 psi |
| Maximum temperature | 250°F |
| Maximum rotation | 30 rpm |
| Threads | 1/4 in NPTF, both ends |
| Body | brass, nickel-plated |
| Standard seal | NBR O-ring |
Note the threads. 1/4 in NPTF is a tapered pipe thread, not M22 or quick-connect, so a consumer hose needs adapters on both sides. Each adapter is another part whose rating has to cover your machine. See NPT vs BSP vs M22 threads.
Swivel adapters
AR Blue Clean's PW554-B is a transfer M22 swivel adapter with a 15 mm M22 swivel inlet and a male M22 x 14 mm outlet, made of aluminum and plastic.[4] AR sells it so a gas-style hose with a 14 mm female connection can attach to the 15 mm male connection found on many electric washers. It is an adapter between two bore sizes; AR's description does not present it as a live swivel. More in M22 to quick-connect adapters.
The weakest part sets the limit
Cat Pumps advises that a high-pressure system is only as strong as its weakest component, so every part must be selected carefully.[5] A swivel rated below your machine's pressure or water temperature is the weak link, and so is any adapter you add to fit it.
Before adding a swivel:
- Name the thread on both ends (M22 with its bore, quick-connect size, or NPT).
- Check the pressure and temperature rating against your machine's maximum.
- For a live swivel, check that the maker states it may rotate under pressure.
- Count the adapters it needs. Each one must carry the same rating.
Next
Questions
What is a live swivel?
A fitting built to rotate while the line is under pressure, so the hose can turn without twisting. A retailer listing for the Mosmatic DGV 32.557, for example, describes it as built for live rotation under full pressure.[3]
Do I need a swivel on my pressure washer hose?
It is optional. Some guns build one in, such as the MTM Hydro SGS28 with its integrated stainless live swivel. If you add an inline one, its threads must match both neighbors and its rating must cover your machine.[1][5]
What PSI is a swivel rated for?
It varies by model. One retailer lists the Mosmatic DGV 32.557 at 4,000 psi, 250°F and 30 rpm; that figure is the retailer's and applies to that variant only.[3]
Is a swivel adapter the same as a live swivel?
Not necessarily. AR Blue Clean's PW554-B is a transfer adapter with a 15 mm M22 swivel inlet, sold to join a 14 mm female hose to a 15 mm male connection. A live swivel is rated to rotate under pressure; unless the maker says so, treat a swivel adapter as a connector only.[4]