Packing Rings

CPI combines a wide variety of materials and designs to meet any specific packing ring requirement - Cast iron, and bronze are just a few of the materials available. All of these materials are available in packing rings designed for unidirectional and bi-directional sealing, low pressure vent sealing, and gas purge sealing. Also available are high speed and high pressure rings.

Packing Assembly and Installation

The assembly of the packing case and rings provides sealing to prevent the escape of gas along the piston rod. Careful handling of the assembly, observing a few simple precautions and following the instructions or drawings in the operator’s manual will prevent damage or loss of compressor efficiency.

Packing Cases

Two methods of installation are used. With either method, the packing case and rings should be disassembled and thoroughly cleaned.Parts should be free of nicks, burrs, scratches, etc. and should be laid out in the order in which they are to be assembled.

Method 1.

In some installations, the packing case with rings may be bolted into the stuffing box completely assembled and the rod plunged through the case making provisions to protect the rings by covering the threads with a sleeve. The entering sleeve should have a tapered end to help center the rings.Caution: Tangent-to-the-rod rings should not be plunged as the tips may be damaged.

Method 2.

Some packing cases must be assembled on a piece by piece basis over the rod end. Parts should be laid out in sequence and each installed in its proper order. Tie rods are provided for aligning oil, vent and coolant passage holes, as well as holding the assembly together during installation. Two or three tie rods are used depending on the size of the case. Tie rods are off-center so that packing cups can be assembled only one way. With the packing assembled in the stuffing box, the flange studs should be tightened as any gasketed joint, applying pressure through opposite studs gradually to obtain even crushing on the gasket. This will prevent cocking of the packing cups and insure their being in a perpendicular plane to the piston rod.

Fully-Lubricated Packing

Packing rings and cups should be coated with the proper lubricant during assembly. Each oil line should have a check valve between the lubricator and the connection to the packing case. This should be as close as convenient to the case connection. Refer to the operator’s manual for recommended break-in procedure. Prior to each compressor start up, the oil line should be filled.

Min-Lube Packing: CPI Filled PTFE and CPI Special Polymer Alloys

During assembly, the CPI filled PTFE and CPI Special Polymer Alloy packing rings and the cups should be coated with the proper lubricant. CPI filled PTFE and CPI Special Polymer Alloy rings can normally be used under full load without the usual wear-in procedures required with metal rings. Initially, a higher rate of lubricant feed should be used. However, this feed rate can be reduced within 24 hours after start up

Non-lube packing: CPI filled PTFE and CPI Special Polymer Alloys

The case and rings are assembled without oil and should be broken in without any oil feed.Check liquid cooled packing cases to assure proper cooling flow.

Vent Connection

Most packing cases are equipped with vents as a safety precaution.These vents may be piped to an approved collection or disposal point. If a sufficient pressure drop does not exist, particularly behind a vent, side loading of the vent rings may be necessary. Consult your CPI representative for further details and technical support.

Packing rings

CPI Packing Rings Brochure