Camlock or NPT: picking the outlet

Camlock couplings

A camlock (cam-and-groove) coupling has two halves. The male half, the adapter, has a groove around it. The female half, the coupler, has two arms with cams. Push the coupler over the adapter, swing the arms down and the cams pull it onto a gasket. The fittings are made to a common US specification, A-A-59326, so camlocks of the same size from different makers fit together.

They are named by type letter. The ones that come up on totes:

Type	One end	Other end
A	Male adapter (groove)	Female NPT thread
B	Female coupler (arms)	Male NPT thread
C	Female coupler (arms)	Hose shank
E	Male adapter (groove)	Hose shank
F	Male adapter (groove)	Male NPT thread
DC / DP	Dust cap (fits a male adapter) / dust plug (fits a female coupler)

Most tote outlets end in a male adapter with a dust cap, so the hose end is a type C coupler.

NPT threads

NPT is the American National Pipe Taper thread (ASME B1.20.1). The thread tapers, so it tightens into a seal as it is screwed in, with thread sealant or PTFE tape. A tote with an NPT outlet takes a nipple, a pipe or any threaded fitting. It is the choice when the tote is connected to fixed pipework, a dosing pump or a manifold and stays connected until it's empty.

The valve itself usually has a coarse thread of its own. Either outlet is an adapter screwed onto it, and either can be changed later.

Choosing

If you…	Ask for
Drain totes with a hose and swap them often	Camlock, male adapter with dust cap
Hard-pipe the tote to a pump or manifold	NPT, female or male as your pipe needs
Fill buckets or small containers by hand	NPT with a short spout or a faucet adapter
Ship totes to customers whose setups you don't know	Camlock, the most common hose connection

How to name it on a request

Give the size, the type and the gender: "2 in camlock, male adapter, with dust cap" or "2 in female NPT". If you aren't sure, a photo of the end of the hose you use now is enough. Mention the gasket material in the camlock too (EPDM, Viton or another); it touches the product like the valve seat does.

Adapters, and why fewer is better

Almost any outlet can be adapted to almost any hose, but each adapter adds a joint that can weep, a step in the bore that can trap product, and something else to lose. Plants that run many totes usually choose one outlet standard and order every tote to it, so a hose from the store fits whatever arrives.

If you must adapt, keep the adapter on the hose, not on the tote, so it stays with your equipment when the tote leaves. Use the same material as the outlet: a brass or steel adapter on a plastic thread can crack the thread if over-tightened, and some products attack brass. Polypropylene, stainless and aluminium camlock parts are all made; choose by the product, as you would the gasket.

Caps and plugs matter as well. A camlock outlet should have a dust cap locked on in transit, and a threaded outlet a plug or cap. They keep dirt out of the valve and are the second seal if the valve is knocked.

Gaskets inside the coupling

A camlock coupler seals on a gasket seated inside the female half. That gasket meets the product every time the hose is connected, so it should be the same compound as the valve gasket: EPDM for most water-based products, Viton for many oils, fuels and solvents, and other compounds for special cases. A gasket that swells, cracks or flattens leaks at the joint and should be replaced; they are cheap and easy to carry spares of.

Short answers

What camlock is on an IBC tote?

Usually a 2 in male adapter (the grooved half) with a dust cap. A hose with a type C coupler connects to it.

Is NPT the same as a garden hose thread?

No. Garden hose thread (GHT) is a straight thread sealed by a washer; NPT is a tapered pipe thread. An adapter joins them.

Can I change the outlet after delivery?

Yes: the outlet is an adapter on the valve. Ordering it fitted saves the job.

What is a type A or type C camlock?

They are the common letter names for camlock parts: type A is a female-threaded adapter, type C a coupler with a hose barb, and so on. Name the letter or describe the mating part.

Why does my camlock leak when the arms are closed?

Usually a worn, missing or wrong gasket, or a coupler and adapter of different sizes or standards. Check the gasket first; it is the cheapest fix.

Is NPT the same as BSP?

No. NPT is the American tapered pipe thread; BSP is the British standard used on many European totes. They look alike but do not seal together.