Quick Disconnects

Deciding Which Coupling to Use

What is Important?

Dry disconnect couplings are designed to prevent the loss of product when disconnecting hose lines and protecting the operator and the environment.

Consideration of the following points will assist in making the best choice of couplings for your application:

• Valve Type Poppet, ball or butterfly. This is often a matter of personal preference but will also affect the performance of the coupling in terms of flow rate and spillage.
• Acceptable Level of Spillage Prevention of spillage on disconnection is the main reason for using dry disconnect couplings, but the acceptable level will vary greatly according to the application and environment. The couplings in this brochure offer a choice according to how critical this factor is.
• Pressure Drop Flow rate will vary greatly from one coupling type to another – indeed the pressure drop on a 2” Butterfly type is hardly greater than on a 3” poppet valve type.
• Interchangeability Are there already couplings in use with which the couplings must interchange? Conversely, it may be important that the new couplings will not mate with existing fittings on site.
• Method of Operation/Ease of Use The position of connection or the familiarity of the operative with the design may make one type of coupling more suitable on a particular site.
• Weight and Size Weight will be important to the operator when moving the hose according to the frequency of connection, while size may be critical e.g. when the coupling must fit within the envelope of an IBC (intermediate bulk container).
• Temperature/Pressure/Media/Nominal Bore The chosen coupling must be available in the required size and pressure rating with materials compatible with the media, temperature and environment.
• Safety for the Operative and the Environment Apart from the level of spillage, prevention of accidental disconnection should be considered. This can be achieved with a mechanical interlock so that disconnection is only possible when the valve is closed.
• Avoidance of Cross Contamination Accidental connection of the wrong hose line can have serious consequences. Mechanical “keying” of the coupling – or the fitting of sensors – is an option in order to prevent this.
• Potential for Abuse Some couplings are more robust than others. For instance, Polypropylene is light and gives excellent resistance to aggressive chemicals but it may not be suitable in applications where the hose line is frequently thrown about.
• Maintenance Unfortunately, mechanical seals and other components do not last forever. On some couplings e.g. Dry Link, the main seals can be changed in situ, whereas other couplings may need to be returned to the workshop for repair with consequent downtime.
• Cost Oh yes, the cost! Apart from the cost of different materials, generally the coupling cost will be inversely proportional to the amount of spillage on disconnection. Put simply, the more critical the application is in terms of loss of product and protection of the operator and the environment, the more expensive the coupling!

This list is not exhaustive – experience has shown that every new application brings different factors to bear in the best choice of dry disconnect couplings. We would be happy to discuss your specific requirements with you in order to provide further appropriate details and guidance with your selection.

Know Your Application

Copy this page and use it as a checklist

At any stage of this process please call us for any help or further information.

To make the best choice of coupling, you need to know your application by way of the following four primary areas:

• The media (and any different states it may have when flowing through the coupling)
• Size requirements (relating to nominal bore sizes of related pipe systems or the surroundings)
• Operating conditions (for the coupling and its environment)
• Coupling functionality (by way of type of valving, allowable spillage, interchangeability or other needs)

The following table expands on these four categories and can work as a checklist to enable you to make the correct choice.