This guide will teach you everything you need to know about pressure washer hose fittings, couplers and adapters.
all the different types, sizes, materials and naming conventions used.
which help you to make the different accessories, couplers and adapters (with 4 examples).
and how to select the right one for your setup.
let’s get started.
Why are pressure washer accessories needed?
A pressure washer attachment connects the pressure washer parts. fits between high pressure hose and trigger gun or between pump and pressure hose to connect properly.
Your pressure washer will come with the necessary fittings, couplers, and adapters to get you up and running right out of the box (99% of the time).
You will only start to need props when:
- want to add accessories (surface cleaner, foam cannon, pressure gauge)
- want to use a different high pressure hose (or extend the length of the one you have)
- want to swivel threaded fittings for quick connection
- want to better avoid hose kinks by using swivel fittings.
Accessories are affordable ($5 to $15), durable, and made to make your life easier. there are hundreds of different accessories to choose from, but only a couple of types you need to know about.
accessories, couplers, adapters
Fittings, couplings and adapters can be considered the same. Sometimes a website will refer to the entire category of connectors as accessories and then to specific types of accessories such as couplers, adapters, or reducers. but it’s confusing and we won’t do it here.
however, we will discuss quick connect fittings and swivel fittings separately.
quick connect (qc) fittings
quick connect fittings twist threaded connections for quick connect/release, making the job of connecting and removing hose quick and easy.
Female quick connect hose fittings (sometimes called sockets) have an o-ring to prevent leaks. The male side (the bottom one in the picture) are sometimes called the plug.
Nowadays, most hoses come with ready-to-use qc connections.
swivels keep the hose from twisting when in use and help unscrew it when you first pull it out.
It works by allowing swivel (spinning) of the hose without you having to twist the spray gun and extension wand in big circles. You can just walk it out and the gun swivel twists out the hose kinks as you walk. It’s one of those fittings you can’t pressure wash without once you try it.
Check out how a swivel fixture works in this video we made:
materials used to make accessories
Consider what an accessory should do:
- needs to be strong enough to withstand 1000 – 4000 psi for (probably) thousands of cycles of use
- needs to firmly connect the parts together and not break despite constant pulling . the user
- must be resistant to corrosion as it contains water, and
- it has to be cheap enough to be a profitable product for business.
Brass, plastic, and stainless steel are the most common materials used in pressure washer hose fittings.
brass is the most common. then plastic (there are plenty of residential electric pressure washers out there). then stainless steel (very common in professional use due to its chemical resistance).
let’s see the pros and cons of each:
Plastic fittings are only to be used for lighter duty electric pressure washers.
- pros – cheap. lightweight.
- cons – prone to cracking and damage.
Brass is by far the most common mounting material for pressure washers. It is an alloy of copper and zinc and with its low melting point it is easy to mold and machine.
- pros – strong. corrosion resistant. easy to machine into different shapes. more affordable than stainless steel.
- cons – more expensive than plastic.
stainless steel has chrome added to prevent rusting.
- pros – best for corrosion resistance. chemical resistant. high strength.
- cons – expensive.
O-rings are used on the female fittings to prevent leaks. the male quick connect fits into the female plug and the o-ring is perfectly sized to prevent leaks.
The main confusion when shopping for accessories is what size you need to get.
- Is it the inside or outside diameter that you measure?
- Do you include the thread in that measurement?
- How precise do you need to be?
even with digital calipers it can be difficult. some fittings are 3/8″, some are 22mm, some are 14mm on the inside diameter (some need to be 15mm), sometimes you will find fittings that deviate from British pipe thread standards and some are labeled like qc f or qc m to confuse .
Let’s take a deeper look at what all the sizes mean in accessories.
how to measure fittings and fittings
To properly measure the fit you need, you’ll need calipers. a tape measure will work but won’t be as good because we’re talking about 1mm differences.
here are the best calipers:
Here are some other things to know when it comes to pressure washer adapters:
male connections (m) vs. female (f)
The male side has a pin or socket that inserts into the female socket or hole. female fittings receive and hold the male connector in place.
pipe thread standards npt vs. bpt/bsp
- npt = national pipe thread. U.S. technical standard for screw threads.
- bsp = British standard pipe. British technical standard for screw threads.
why should you care about npt and bsp?
because sometimes a pressure washer coupler will be npt and other times it will be bsp. they don’t fit together.
for example: a 3/8″ npt pipe size has a thread pitch of 0.05555 inches (1.411 mm) and an outside diameter of 0.675 inches (17.145 mm). that same 3/8″ bsp pipe has a thread pitch of 0.0526 inches (1.337 mm) and an outside diameter of 0.6560 inches (16.662 mm).
they are similar but not exact and you will not be able to convert a 3/8″ male npt screw connection to a 3/8″ female bsp connection more than 3 or 4 turns before it locks.
internal versus external diameter
When measuring, you must take into account the internal and external diameters of the fitting. m22 threaded connections on gas pressure washers will have an internal diameter of 14mm, but the same m22 on an electric will have an internal diameter of 15mm.
the different sizes you will see: m22 threads, 3/8″ threads and quick connections
Major accessory sizes seen are shown below with digital calipers to show dimensions.
m22 threads are common on pumps, hoses and spray guns
the outer diameter is 22mm, the inner diameter is 14mm, and the inner m22 female side connector is 14mm. the female side has the o-ring to prevent leaks.
It should also be noted that an m22 is also used in electric pressure washers, but it has an internal diameter of 15mm.
3/8″ bsp thread size
this is a british standard pipe thread (bsp) naming convention. is the imperial name of the accessory size but not the accessory size (yes, weird). the actual size of the main diameter of a 3/8″ bsp thread is around 16.66mm (~2/3 inch).
quick connect plug and socket sizes
all the quick connects we have seen have been 3/8″ qc. you don’t need to remove the clips for quick connects.
4 examples to show accessories in use
Now that you know the types and sizes of fittings, adapters, and couplings, let’s look at examples (with pictures) of them in everyday use.
1.) quick connect fittings to make connecting the high pressure hose to the pump quick and easy
In this example, you can see how a pressure washer hose with an m22 style hose connection can be converted to a quick connect with a single fitting: a male m22 thread to a 3/8″ female quick connect socket . then connect a fitting with a quick connect male plug to the pump outlet and you’re good to go.
take a look:
2.) m22 double male coupling to extend the length of two high pressure hoses
Use this simple coupling to connect two m22 female connection hose ends. It makes it so you don’t have to move the pressure washer around all the time, since you have more leeway with the longer hose.
take a look:
3.) quickly connect the hose to the spray gun
These are the same two attachments used in example #1, except for the spray gun end. 3/8 inch QC couplings allow for much quicker installation and removal of the spray wand from the hose when needed.
see how they fit together:
4.) multiple accessories to insert the pressure gauge between the spray gun and the hose
We test pressures on pressure washers, so we need to insert a pressure gauge into the assembly. The gauge has quick connect fittings, so the proper adapters are required to make the spray gun and hose connect quickly.
It is a robust configuration and is usually inserted into the pump to decrease weight on the spray gun:
accessories in electric pressure washers (are they different?)
Some residential electric pressure washers have custom accessories (for that brand). therefore, if you want to replace the spray gun or hose, you will often have to replace it with one of the same brand.
another thing to note is that when they have a m22 screw connection, the internal diameter will generally be different than m22 on gas.
see here (gas pressure washers will have m22 with 14mm internal diameter):
Electric pressure washer coupler will have 15mm inner diameter instead of 14mm. that means if you are trying to connect the hose from your gas machine to the electric, the female connector on the hose will have a 14mm o-ring and the electric spray wand will have a 15mm internal diameter. there is 1mm gap, it will be filtered.
what accessories, couplers and adapters are best to have?
There are two types of accessories that must be owned (in our opinion). quick connect couplers and gun swivels. both make pressure washing more enjoyable and easier.
quick connect couplers
quick connects make it much easier to connect and disconnect the hose from the spray gun and pump. with the screw connection it takes 15 seconds longer and is difficult to do with one hand. In general, for just a couple of dollars it can make your life easier.
check out the best couplers on amazon here…
Gun swivel attachments are great. they prevent and unscrew the hose, which is amazing. You’ll know what I mean if you’ve ever dealt with 50 feet of hose. wrangle the hose when pressure washing can be avoided. with a spinning gun.
view swivel guns on amazon here…