Compression Style Pneumatic Fittings (Parker Poly-Tite)


Poly-Tite is a compact brass compression fitting using a plastic sleeve. It is designed for quick installation in pneumatic instrumentation circuits, lubricant and cooling lines and other applications for liquids and gases. Fittings are supplied assembled, ready for installation. Bodies and nuts are brass (CA 377, CA 360, CA 345) while the sleeves are acetal copolymer plastic.

Pressure & Temperature Range

Up to 150 psi from 0° to +150° F with thermoplastic tubing. Up to 300 psi from 0° to 175° F with soft metal tubing.

Tubing Material

Polyethylene, polypropylene, and vinyl. For nylon and soft metal tubing use a 61PB brass sleeve and wrench tighten one turn past finger tight. Maximum tube wall thickness is .035 for 1/4" and .049 for 5/16”, 3/8” and 1/2" OD tubing.

Special Fittings

Fitting configurations and sizes other than standards can be designed and supplied.


Cut tubing with a PTC-001 cutter so that the end is as square as possible. Soft metal tubing should be cut squarely and deburred. Push tubing into the fitting until it stops and then tighten nut finger tight – no tools needed. To achieve maximum working pressure, one turn with a wrench past finger tight will afford a more secure joint.

Fitting makeup is achieved by turning the nut which bears against the back of the sleeve, causing the sleeve to move forward against the radiused ramp machined into the bore of the body. Tube twist is prevented because the sleeve provides a rotational surface that allows rotation of the nut to be translated into straight forward movement of the sleeve. Turning torque is not translated to the tube. As the sleeve moves forward, it is forced inward against the tube and traps the tube against the built in tube support.

Sealing is achieved at two points – between the tube and the sleeve and between the sleeve and the body. Mechanical retention of the tube is achieved by the compression of the tube between the sleeve and the tube support. Note that resisting blow out caused by the system pressure is seldom a problem in small diameter, low pressure fittings. Blow out force (F) is a function of the pressure (P) times the area (A) presented by the end face of the tube. Typically, 150 psi acting against the .049 square inch area of a 1/4" tube generates 7.36 lbs. of force. The black acetal copolymer is compounded to resist ultraviolet attack and stress and creep caused by compression.


Loosen nut and pull line back from fitting. Unless they are over tightened and distorted, Poly-Tite fittings can be repeatedly assembled and disassembled.

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