A Guide To Camlock Couplings

Camlock couplings facilitate the transfer of commodities between two hoses or pipes. They are simple to connect and disconnect, requiring no tools. Camlock couplings are used across industries, such as manufacturing, agriculture, oil, gas, chemical, pharmaceuticals, and military applications. Camlock couplings, also called cam and groove couplings, are perfect for dirty environments and well suited for situations in which frequent hose changes are required, such as petroleum and industrial chemical trucks.

Table of contents

• How do Camlock couplings work?
• Camlock coupling types
• Selection criteria for Camlock couplings
• Camlock coupling standards for manufacturing
• Camlock coupling accessories
• Special Camlock couplings
• Camlock coupling safety & preventative maintenance

How do Camlock couplings work?

The assembly of a Camlock coupling consists of two pieces: a male plug and a female coupler. Figure 2 shows the components and process for connecting and disconnecting Camlock couplings.

• The coupling handle should be extended outward, and the correct male plug should be placed into the female coupler (Figure 2 labeled A).
• The two halves should be firmly locked together by closing both handles simultaneously (Figure 2 labeled B). Closing both handles simultaneously ensures that the grooved plug is consistently pushed down onto the seal, guaranteeing a leak-proof assembly for the safe transfer of liquids.
• Ensure that the camlock hose assembly is de-pressurized before reversing the process to disconnect the fitting (Figure 2 labeled C).

Camlock coupling types

Camlock couplings are identified by their type designations, which are listed below while the image shows a visual reference for the various coupling types.

• Type A: Plug with female thread
• Type B: Coupler with male thread
• Type B-AS: Coupler with weld end
• Type C: Coupler with hose tail
• Type D: Coupler with female thread
• Type E: Plug with hose tail
• Type F: Plug with male thread
• Type F-AS: Plugs with weld connection
• Type DC: Dust cap for plugs
• Type DP: Dust plug for couplers
• Type DA: Female coupler with male camlock adapter

Selection criteria for Camlock couplings

Before purchasing, various factors should be considered to get the correct fitting for the application. Below is a list of the primary selection criteria for Camlock couplings.

Size

Camlock coupling sizes are determined by their nominal size, where the male and female couplings have slightly different sizes for coupling purposes. The male plug (Figure 3 labeled B) is measured on the outside, while the female coupler is measured on the inside (Figure 3 labeled A).

Table 1: Camlock coupling size chart

Nominal size (inch)	A (mm/inch)	B (mm/inch)
3/4	32.4 / 1.28	32.1 / 1.26
1	37.3 / 1.47	36.7 / 1.44
1 1/4	46.0 / 1.81	45.5 / 1.79
1 1/2	54.0 / 2.13	53.4 / 2.10
2	63.8 / 2.51	63.0 / 2.48
3	92.2 / 3.63	91.5 / 3.60
4	120.3 / 4.74	119.5 / 4.70

Temperature

The temperature specifications of the coupling are determined by the material chosen. For example, 70 °C (158 °F) is the maximum temperature that polypropylene can handle, at which pressures must be reduced by 40%. When stainless steel is used, the operating temperature ranges from -150 °F to 500 °F (-101 °C to 260 °C). Due to these differences, it pays to know the application's exact details and working temperatures. Remember that the minimum and maximum operating temperature depends on various factors besides the material the Camlock coupling is made of. These include, but are not limited to the operating pressure, media used, outside factors like weather, etc.

Material

Table 2 illustrates the advantages and disadvantages of each material and how they can use it for various applications.

Table 2: Camlock fittings chart with materials

Coatings

Camlock couplings are specially coated to protect them from highly aggressive chemical agents. This is because some standard materials, like stainless steel, cannot withstand those situations. For example:

• ECTFE (ethylene chlorotrifluoroethylene): Couplers coated in ECTFE demonstrate excellent electrical insulation, fire, and corrosion resistance, and can withstand temperatures up to 150 °C. These couplings have been designed to resist highly concentrated and aggressive chemicals.
• PFA (Perfluoroalkoxy alkanes): PFAs are particularly well suited for food and pharmaceutical industries because of their high-temperature resistance.
• PTFE (Polytetrafluoroethylene/ Teflon): These coatings can withstand temperatures up to 260 °C and are as effective as PFA coated couplings for food-grade applications.
• PVDF (Polyvinylidene difluoride): The coatings are wear-resistant and are also suitable for food industry applications. They are resistant to highly concentrated and aggressive chemicals and have the advantage of high temperature resistance up to 260 °C.

To learn more about the chemical properties of various materials, read our article on the chemical resistance of materials.

Maximum operating pressure

For the maximum operating pressure ratings for Camlock couplings, see the below table. The pressure rating is the pressure at ambient temperature.

Table 3: Camlock pressure rating characteristics

Nominal couplings size/ material	1/2"	3/4"	1"	1 1/4"	1 1/2"	2"	2 1/2"	3"	4"	5" – 6"	8"
Aluminum PSI	150	250	250	250	250	250	150	125	100	75	150
Aluminum Bar	10.34	17.23	17.23	17.23	17.23	17.23	10.34	8.61	6.89	5.17	10.34
SS 316 PSI	150	250	250	250	250	250	225	200	100	75	-
SS 316 Bar	10.34	17.23	17.23	17.23	17.23	17.23	15.51	13.78	6.89	5.17	-
Brass PSI	250	250	250	250	250	250	150	125	100	75	50
Brass Bar	17.23	17.23	17.23	17.23	17.23	17.23	10.34	8.61	6.89	5.17	3.44
PP PSI	75	100	100	100	100	100	-	50	50	-	-
PP Bar	5.17	6.89	6.89	6.89	6.89	6.89	-	3.44	3.44	-	-
Nylon PSI	-	100	100	100	100	100	-	50	50	-	-
Nylon Bar	-	6.89	6.89	6.89	6.89	6.89	-	3.44	3.44	-	-

Camlock coupling standards for manufacturing

A-A-59326D (previously Mil-C-27487)

Mil-C-27487, now superseded by A-A-59326D, was the US military specification for Camlock couplings. Although the original standard was replaced with a new one, the US still guaranteed the interchangeability of couplings of the same design. Mil-C-27487 specifies the casting processes, materials, dimensions, tolerances, pressure ratings, and inspection procedures.

EN 14420-7

EN 14420-7, the European standard developed to replace the American Military standard was ratified by the European Committee For Standardization, CEN, in September 2004. Cam locking couplings are manufactured worldwide according to the American military specification. However, this American standard fixes only the coupling side, not the connection side. Other parts, like levers, bolts, rings, and seals, are not standardized. EN 14420-7 seeks to correct this.

Interchangeability

Except for 12”, 5” and 8”, Camlock couplings are interchangeable between manufacturers. Since there are two types of Camlock couplings on the market today, the A-A-59326A military specification does not apply to 5” and 8” cam & groove couplings.

There are some differences between Camlock couplings produced to EN 14420-7 and those produced to the original MIL-C-27487 standard in terms of hose tail design, thread, and part number. A flat thread seal has been added to the female threaded parts, and a smooth hose shank in accordance with EN 14420-7/DIN 2828 has been added for use with safety clamps that comply with EN 14420-3/DIN 2817.

Camlock fitting manufacturing quality

It is important to know your supplier of the Camlock coupling. Even if they are made to the same standard, slight differences in the manufacturing method might make the couplings from one manufacturer not suitable for another. This is typically only an issue if dealing with cheap Camlock couplings. Ensure the couplings are of high quality and from a reputable manufacturer. Ideally, the plug and coupling side of the connector are from the same manufacturer.

Camlock coupling accessories

Gaskets & seals

All metal Camlock couplings and polypropylene Camlock fittings are supplied & fitted with either a NBR, EPDM, or a PTFE (teflon) seal. Different sealing compounds are available depending on the media being conveyed through the couplings. There are replacement seals available made of the following materials:

• FKM (FPM)
• CSM (Hypalon)
• Teflon PTFE/NBR compound
• Teflon PTFE/FPM compound

For applications requiring more exotic sealing solutions, chemical encapsulated seals are available made of silicone or FEP.

R clips

The R clips are designed to be used with Camlock couplings to prevent accidental disconnection of the coupling assembly. As seen in Figure 6, the R clip (Figure 6 labeled A) can be pushed through a hole (Figure 6 labeled C) behind the handle (Figure 6 labeled B) to prevent the handle from becoming loose once the plug is connected to the coupling. R Clips are only used as a safety feature to prevent the two halves of a Camlock coupling from catching on something or working their way loose.

Lock system

An alternate design of Camlock couplings with automatic locking arms has been devised to prevent unintentional disconnection, which would result in spillage. This is important, mainly if the medium contains highly flammable or toxic liquid chemicals. The Camlock fitting shown in Figure 7 is modified to have a built-in automatic locking system.

In this way, it is similar to a standard Camlock fitting, but with the added security of locking securely into place and preventing accidental opening when opened.

Special Camlock couplings

Special Camlock fittings are available for non-standard applications. This section provides an overview of the less common Camlock couplings and where they are used.

• Undercut DIN 2828: In general, the Undercut DIN 2828 is used where the male thread on a hose is parallel and offers an undercut at the base of the thread as well as a gasket for the male thread to sit on.
• Flanged: Flanged ends are available with Camlock couplings so that the quick release system can be introduced without the need to make major alterations to the pipework.
• Spiral tail camlock couplings: Spiral tail and helical tail couplings can be used in composite hoses to match the internal helix of the hose. A swagged ferrule secures the couplings to the composite hose.
• Camlock plug & caps: Dust Plugs (Type DP- Dust Plug for Couplers) and dust caps (Type DC- Dust Cap for plugs) can be used with types B, C and D to seal the end of the connection.
• Smooth tail coupling EN14420-7 (DIN2828): The smooth tail of the part C and part E couplings have an annular collar, making the BS EN14420-3 clamp, which has a lip, engage behind the collar. By doing this, there is less risk of a hose blowoff.
• Safety bumps for camlock couplings: Safety bumps are mechanisms designed to prolong the life of the Camlock fittings and keep the hose assembly clean when not in use and help prevent spills.
• Safety locks for camlock couplings: Camlock coupling arms will not inadvertently open if safety locks are used. They are an alternative to more expensive locking handles, and they are easy to install and easy to remove, too.
• Camlock coupling chain: These chains can be used to attach a DP dust plug or DC type dust cap to a type B, C, and D coupling or plug.

Camlock coupling safety & preventative maintenance

Have a routine maintenance schedule to inspect the Camlock couplings frequently. It is important to regularly check and replace worn parts on Camlock couplings since moving parts are subject to wear and tear. By replacing worn parts, one can extend the life of the products and ensure health and safety standards are met.

FAQs

What is a camlock hose?

A camlock hose is a hose equipped with camlock couplings, which allow for quick and tool-free connection and disconnection, facilitating the transfer of commodities.

What are stainless camlock fittings?

Stainless camlock fittings are durable, corrosion-resistant couplings made from stainless steel, ideal for harsh environments and applications requiring high hygiene standards.

What are aluminum camlock fittings?

Aluminum camlock fittings are lightweight, cost-effective couplings made from aluminum, suitable for general-purpose applications and less corrosive environments.