Camlock Fittings Guide: Types A Through DP, Explained

Written by the Apex Flow Solutions technical desk — twenty years of industrial distribution experience behind every guide.

Camlock — cam-and-groove — couplings let you connect and disconnect large-bore lines by hand, no wrenches, no threads to cross: a quarter-turn of two lever arms locks the joint or breaks it. That's why every tanker offload, IBC tote transfer, chemical feed line, and irrigation mainline crew reaches for camlocks instead of threaded pipe. The trade-off for that speed is a type-letter system that trips up a lot of first-time buyers — A, B, C, D, E, F, DC, DP aren't sizes or materials, they're connection types, and ordering the wrong letter is the single most common camlock mistake we see at the quote desk. This guide explains what each letter actually means, how the two halves mate, why parts from different brands still fit together, and links the real Apex products behind each type across aluminum, polypropylene, and stainless.

Buying Summary — What You Need, By Situation

I need to… Get this Why
Connect a hose to a pipe with male external threads Type C on the hose + Type A on the pipe Type A's female NPT threads onto the male pipe end
Connect a hose to a tank or valve port with female internal threads Type C on the hose + Type F on the port Type F's male NPT threads into the female port
Join two hose ends together Type C on one hose + Type E on the other One coupler half, one adapter half — that's all a joint needs
Connect two straight pipe runs, both male-threaded Type A on one pipe + Type D on the other Both ends thread onto male pipe; the camlock halves mate to each other
Protect an open coupler when the line's disconnected Type DC dust cap Keeps grit out of the lever mechanism and sealing face
Protect an open adapter when the line's disconnected Type DP dust plug Same protection, sized for the adapter's groove ring

The Two Halves: Coupler vs. Adapter

Every camlock size has two mating halves. The coupler carries the two lever arms — that's the piece people picture when they hear "camlock." The adapter carries the raised groove ring the arms lock onto. Any coupler mates with any adapter of the same nominal size, regardless of type letter or manufacturer, because both halves are cut to the same standard coupling profile — more on that below.

What actually changes between the type letters isn't the camlock end at all — it's the other end: a female NPT thread, a male NPT thread, or a barbed hose shank. So the whole system reduces to two decisions: pick your camlock half (coupler if you want the lever arms, adapter if you want the groove ring), and pick the other-end connection to match whatever you're attaching to. Type DC and DP aren't couplings at all — they're protective caps and plugs that thread onto an open coupler or adapter to keep contaminants out of the sealing face between hookups.

Type A — Male Adapter, Female NPT

Adapter half (groove ring, no lever arms) with a female NPT thread on the back end — screws onto a male-threaded pipe nipple, valve outlet, or pump discharge. Mates with any B, C, or D coupler.

Type B — Female Coupler, Male NPT

Coupler half (the two lever arms) with a male NPT thread — threads into a female-threaded port on a tank, manifold, or pump. Mates with any A, E, or F adapter.

Type C — Female Coupler, Hose Shank

The one you'll use on the most hose ends: coupler half plus a barbed shank for a hose clamp. Mates with any A, E, or F adapter.

Type D — Female Coupler, Female NPT

Coupler half plus a female NPT thread — screws onto a male-threaded pipe stub. Mates with any A, E, or F adapter.

Type E — Male Adapter, Hose Shank

Adapter half plus a barbed hose shank — the piece that lets two hose ends connect to each other through a Type C coupler.

Type F — Male Adapter, Male NPT

Adapter half plus a male NPT thread — threads into a female-threaded port.

Type DC — Dust Cap

Protects an open coupler (B, C, or D) when the line is disconnected — keeps grit and debris off the lever mechanism and the gasket face so the next hookup seals clean.

Type DP — Dust Plug

Protects an open adapter (A, E, or F) when the line is disconnected — same job as the DC cap, sized for the adapter's groove ring instead of the coupler's arms.

The MIL-C-27487 Interchange Standard

Cam-and-groove dimensions trace back to MIL-C-27487, the U.S. military specification that standardized coupling and groove dimensions so couplers and adapters from different manufacturers interchange at a given nominal size. That standard — not the brand name cast into the lever arm — is why a Type C coupler from one maker locks cleanly onto a Type A adapter from another. Apex's camlock line (Midland Industries) is built to these standard dimensions, and each product page notes it. It's also why the type-letter designations themselves (A through F, DC, DP) are consistent across the whole industry: this is the same lettering system you'll see on any cam-and-groove line, not an Apex-specific code.

Quick Reference — All 8 Types

Type Camlock half Other end Mates with
A Adapter Female NPT Any B/C/D coupler
B Coupler Male NPT Any A/E/F adapter
C Coupler Hose shank Any A/E/F adapter
D Coupler Female NPT Any A/E/F adapter
E Adapter Hose shank Any B/C/D coupler
F Adapter Male NPT Any B/C/D coupler
DC Dust cap — Fits any open coupler (B/C/D)
DP Dust plug — Fits any open adapter (A/E/F)

Sizing and Material — Two More Decisions

Picking the type letter only answers "what does each end connect to." You still need to confirm the actual nominal size matches your hose or pipe — a "2 in." camlock is a label, not a caliper reading, and the two sizes never lock together even when forced. See Camlock Sizing: Why Camlock Size Isn't Hose ID for how to check that before you order. And the body material — aluminum, polypropylene, or stainless — changes which chemicals and services the fitting can handle; see Camlock Materials: Aluminum vs Polypropylene vs Stainless. Every camlock joint also depends on the gasket inside the coupler doing the actual sealing — covered separately in Camlock Gaskets: Buna-N vs Viton.

Frequently Asked Questions

What's the difference between a camlock coupler and an adapter?

The coupler carries the two lever arms that lock the joint. The adapter carries the raised groove ring the arms lock onto. You always need one of each to make a connection — never two couplers or two adapters together.

Do all camlock brands interchange?

Within the same nominal size, yes — that's the point of the MIL-C-27487 standard. A coupler from one manufacturer mates with an adapter from another as long as both are built to the standard dimensions for that size.

Which type do I need to connect a hose to a threaded valve outlet?

Put a Type C coupler on the hose end. On the valve outlet, use a Type A adapter if the outlet has male external threads, or a Type F adapter if the outlet has female internal threads.

What's the difference between a DC dust cap and a DP dust plug?

DC caps fit over an open coupler (the lever-arm half). DP plugs fit into an open adapter (the groove-ring half). They're not interchangeable with each other — match the cap or plug to whichever half is sitting open.

Related Guides

Type-letter definitions and the coupler/adapter interchange principle are standard, widely published cam-and-groove reference information derived from MIL-C-27487. Confirm the exact size and material against the product page before ordering, and ask us before specifying for a chemical service outside plain water or general transfer.

Not sure which type or material your application needs?

Send us what's on each end of the connection — hose, pipe thread, or tank port — and what's running through it. Request a quote and you'll have the right part numbers confirmed by a person the same business day.

Technical data disclaimer: Specifications, dimensions, pressure/temperature ratings, and compatibility information on this page are compiled from manufacturer publications and are provided for reference only. Always verify suitability for your application against the manufacturer’s current documentation before purchase or installation. Apex Flow Solutions assumes no liability for errors, omissions, or misapplication of this information.