Plunger Pump Seals & Packing

Crosshead Seals

The main function of the crosshead seal is to prevent oil escaping from inside of the pumps crankcase whilst simultaneously preventing ingress of water, dirt or other contaminants inside the crankcase. PSS Technologies can offer crosshead seals in a variety of sizes and materials and we also offer custom seals designs that are best matched to your existing crosshead and crankcase recess dimensions. Please contact us with your requirements and we can guide you through the selection process.

Low Pressure Seals

Low pressure seals are generally found between the crosshead and wet end of the pump and their primary function is to prevent leakage of pumped fluid to atmosphere, whilst also complimenting the performance of the high pressure sealing assembly (shown below). The importance of the low pressure seal cannot be overstated, particularly when there is limited space available, high pump running speeds or poor lubrication. PSS Technologies can supply elastomer based low pressure seals which are easy to install and maintain and have dry running capability to reduce the demand placed on internal lubrication requirements. By choosing the right low pressure seal and material for your application, this will ensure that your pump has a longer service life as well as reduced low-pressure leakage. Please contact us with any low pressure sealing requirements and we can guide you through the selection process.

High Pressure Sealing Assemblies

High pressure sealing assemblies, otherwise known as “Stuffing Box” sealing assemblies are critical to the operation of the plunger pump and play a major role in the assurance of adequate down-stream fluid pressure. The packing rings (yellow & black) provide a seal around the reciprocating plunger and allow proper alignment of the plunger to reduce wear, improve flow conditions and extend the overall service life of the pump. The tolerances of the stuffing box bore need to be closely controlled to allow for correct fitting of the packing rings and sufficient sealing against the plunger without excessive wear. Anti-extrusion rings and compressions springs hold the packing material in place and help to keep the rings “energised” so that a seal against the plunger outer surface can be maintained at all time. At PSS Technologies, we can supply individual sealing components or fully assembled, high pressure sealing cartridges for hassle free installation. Whatever your requirements, please get in touch and we will be happy to propose the best sealing solution to meet the demands of your application.

High Pressure Face Seals

Static O-ring Face Seals are designed to seal high pressure fluids (up to 690 Bar) in face mounted assemblies, and provide a perfect drop-in replacement for O-rings in seal glands. The face seal consists of an L-profiled elastomeric sealing element combined with an energized anti-extrusion ring. At low pressures, the elastomeric ring provides a positive seal. As pressure builds, the system pressure is transferred to the anti-extrusion ring which pushes it towards the outer gland wall, sealing any extrusion gap. At PSS Technologies, we offer face seals in a range of different materials and sizes and can even provide custom seals to suit your application.

Plunger Pump Packing

Plunger pump packing, also know as ‘gland packing’ is a braided packing material that is ‘packed’ in to the space between the plunger and inner bore wall of the plunger pump housing, to create a high pressure seal. The main function of the packing is to remain stationary and prevent leakage of the pressurised fluid to atmosphere as the plunger reciprocates, without generating too much friction and heat. The compressed packings are typically made from PTFE filaments or acrylic fibre and exfoliated graphite, and are often impregnated or coated with lubricating materials for enhanced performance. This provides the packing with low-friction, self lubricating properties to ensure that the plunger travels in a free and smooth manner. They also exhibit excellent chemical resistance to acids and alkalis and when compressed, provide a hard wearing, yet flexible product to ensure consistent performance with varying plunger speeds, temperatures and pressures. Packing materials can be supplied as individual custom made die-formed rings, or ready to fit pre-compressed packing sets for ease of assembly. Please send through your process details and or engineers will be able to select the best packing rings for your application.

For any enquiries related to plunger pump seals and packing materials, please contact

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