Technical Specification - Polypropylene Fittings and Valves
NOTE: This specification refers exclusively to our white polypropylene fittings and valves prefixed PP. Other fittings, valves, tube and ancillary products have their own Technical Specification.
Product Selection and Installation
John Guest fittings and related products are specifically designed and manufactured by John Guest to the Technical Specification set out in the John Guest Product Catalogues. All John Guest fittings and related products should be selected, installed, used and maintained in accordance with these Technical Specifications. It is the customer's/user's responsibility to ensure that John Guest fittings and related products are suitable for their intended applications, are properly installed and maintained and are used in accordance with the Technical Specifications. It is also the customer's/user's responsibility to provide its own customers with all relevant technical information about John Guest products it supplies them. If you have any questions about our technical specifications, please contact us.
For use with chemicals or other potentially aggressive liquids, please refer to our Customer Services Department.
Super Speedfit fittings and related products are not recommended for use with explosive gases, petroleum spirits, and other fuels or for central heating systems.
Maintenance and Replacement Intervals
John Guest products generally require little maintenance but as a minimum we recommend routine visual inspection. Frequency of visual inspection will depend on severity of application and risk of failure. If after visual inspection John Guest products appear damaged, cracked, charred, discoloured, heat distorted or corroded they should be replaced. Any product that is or appears to be leaking should be replaced.
Product life is affected by the severity of the application, the hostility of the working environment and contact with aggressive chemicals or liquids. It is therefore important that specific replacement intervals be considered by specifiers/users/customers based on previous service life or when failure could result in unacceptable downtime, damage or injury risk.
Installation and System Testing
Fittings and tube should be kept clean and undamaged before use.
All tube and fittings installations must be pressure tested after installation to ensure system integrity before handing over to the final user.
Working Pressure and Temperature Range
John Guest Polypropylene fittings are suitable for the following pressures and temperatures.
Minimum temperature 1°C
Depending on the tube used, under certain conditions fittings may be used at higher pressures and temperatures. Please refer to our Customer Services Department for guidance.
Note: 1 Bar = 14.5 PSIG.
Plastic Tube - Polyethylene, nylon and polyurethane conforming to the tolerances shown below. For soft tubing or thin wall tube we recommend the use of tube inserts.
Braided Tube - Use of Tube to Hose Stems is essential when using braided tube. Use of clamps to retain braided tube on barb is recommended.
Metal Tube (soft) - Brass, copper or mild steel conforming to the tolerances below.
Metal Tube (hard) - We do not recommend Super Speedfit fittings for hard metal tubes or chromium plated tube.
For stainless steel and other polished metal tubes we recommend the use of SuperSeal fittings.
It is essential that outside diameters be free from score marks and that the tube be deburred before inserting the fitting.
Super Speedfit fittings are offered for tubes with outside diameters to the following tolerances.
| Size (inches)
|| 5/32 - 3/16
|| 1/4 - 1/2
||+0.001 / -0.003
||+0.001 / -0.004
| Size (mm)
|| 4mm - 5mm
|| 6mm - 22mm
| Tolerance (mm)
|| +0.05 / -0.07
|| +0.05 / -0.10
1/4 Turn Valves
These valves have been designed to allow temporary servicing of downstream equipment and must only be used in the fully open or fully closed position. DO NOT USE THESE VALVES: In a partially open position to control flow; to provide a permanent termination; without tubing assembled or plugged (or threaded connections sealed) or as a tap or "faucet".
Are available as additional security against removal of the tube or to provide a simple means of colour coding. The cover is offered in a range of six colours.
|All these fittings are produced in Food and Drug Administration (FDA) compliant materials and are therefore recommended for food quality applications.
Maximum Torque Values for Plastic Threads BSP, BSPT & NPT.
Do not overtighten plastic threaded fittings as this could cause undue stress and eventual failure. Maximum recommended torque figures are shown below.
|1/8 - 1/4
||3/8 - 1/2
John Guest recommend OEM customers to consider replacing threaded ports with the more modern Cartridge Systems.
It is recommended that all installations are checked prior to use to determine that a seal has been made.
The maximum torque figures quoted for use with Speedfit fittings are dependant on the mating thread conforming to the relevant British or International thread standard.
For use of with chemicals or potentially aggressive liquids, please refer to our Technical Service Department.
NOTE: When using cleaning agents or other potentially aggressive liquids, please ensure compatibility with tubing and fittings.
Whilst we give a warranty against defects in manufacture or materials, it is the responsibility of the specifier to ensure that fittings and related products are suitable for their application. The installation must be carried out correctly in accordance with our recommendations, complying with recognised codes of practice and relevant national standards, and be properly maintained. Please refer to our terms and conditions of sale.