May 22, 2024

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Things to Consider Before Purchasing Hydraulic Piston Seals

Hydraulic Piston Seals


Let us start by unfolding what a hydraulic seal is all about. It is a soft, non-metallic ring, usually built in a groove or fixed in a combination of rings.

The combination forms a seal assembly to block fluid during motion. The importance of the seals in machinery applications lies in providing a means of converting fluid power into linear motion.

Different materials are used for making hydraulic seals. And, the most common materials are polyurethane, rubber or PTFE.

Choosing the material depends on the particular operating conditions on account of the fluid type, pressure, fluid chemical temperature or compatibility.

Static and dynamics–these are the major variants of hydraulic seals in the market.

A static hydraulic seal does not move, and is confined in a groove, like a gasket. It has to be under pressure, arising from tightening of the bolts.

On the other hand, the dynamics variant, also called a rod seal, moves on its inner diameter along the shaft or rod of a hydraulic cylinder.

Fluid cannot get through the piston head area due to hydraulic piston seals. Rod seals prevent fluid leaks from the cylinder and that sufficient pressure is maintained.

There are also wiper seals to prevent contaminants from entering the hydraulic system. And, a rod seal restricts fluid from leaking beyond the sealing system.

Additionally, rod seals assist in reducing environmental contamination when used in conjunction with a wiper seal.

A hydraulic cylinder’s tube or bore exposes a piston seal to movement on its outer diameter. Depending on the sealing application, different piston seal variants provide different advantages. Environmental factors such as temperature, pressure, stroke speed, and others might influence the choice of variants and materials by users.

How to Choose Right Hydraulic Seals

Remember, buying a hydraulic piston seal is not a straightforward affair. Instead, you should consider a slew of factors beforehand.

Before seals can be selected certain application parameters and information should be collected. The following most common application considerations are nearly always required when selecting hydraulic seals:

Fluid pressure range: the operational fluid system pressure range, pressure peaks’ frequency and severity

Temperature range: the extent of the fluid and cylinder assembly

Speed: the speed at which the piston strokes on the reciprocating piston rod

Fluid media: the viscosity and type of fluid in the system

Hardware Dimensions: the operational fluid system pressure range, pressure peaks’ frequency and severity

Application of the cylinder: installation, duty cycles, environmental variables such outside temperature, and pollutants also the kind of equipment the cylinder will be handling and how it will work in that equipment.

Hydraulic Seal Materials

Different materials are used to make hydraulic cylinder seals. And each material has intrinsic properties that make them suited to different conditions, including high temperatures and pressures, and caustic chemicals.

Here is the list of materials, commonly used for making hydraulic seals:


In situations when a high level of flexibility and compressibility is required, rubber seals are used.

Hydraulic seals are commonly made from nitrile butadiene rubber (NBR), fluoroelastomer (FKM), and hydrogenated nitrile butadiene rubber (HNBR). Grease, mineral oils, and other hydraulic fluids are well tolerated by them.

Polytetrafluoroethylene (PTFE)

Under severe conditions, such as temperature, pressure, and caustic chemicals, PTFE offers higher durability. Additionally, because PTFE has a relatively low coefficient of friction, it requires less lubrication than other seals and may operate effectively in dry conditions.


Plastic hydraulic cylinder seals, which come in a variety of materials, provide moderate resistance to temperature, pressure, and chemical reactivity.

The strength of a plastic seal is mostly determined by the material’s quality, which can range from high-performance plastics to designed polymers, which are superior to commodity plastic. These seals increase the strength of your cylinder because they are less flexible than rubber or PTFE.


Therefore, you should do the due diligence of selecting the proper hydraulic seal for your business. By now, you have come to know what hydraulic seals are all about.