Seals play a very important role in the function, design and service life of hydraulic cylinders and systems. Piston Seals performs the function of providing leak-proof system, resistance to wear and tear, resistance to high and temperatures, low friction, and easy installation. Industries, based on their application choose the material for the piston seal in order to limit the extent of properties required for the optimization of the system functioning. Piston seals are commonly used for shutting gaps or sealing of joints for hydraulic or pneumatic cylinders. Hydraulic piston seals come in different sizes and materials based on the application, the systems are subjected to. Piston seals are generally soft and smooth on the surface, non-metallic rings which get seated into the groove forming a seal assembly to separate fluid in reciprocating motion applications. Their use is vital for fluid power to be converted to linear motion without any losses. 

They are generally made of a variety of materials such as rubbers, polyurethane. They are basically dynamic hydraulic piston seals called rod seals that are exposed to movement along with the piston on the inner diameter of the hydraulic cylinder. The type of seal used depends upon the way the cylinder operates i.e. Single-acting Pistons and Double-acting pistons. The seals on the single-acting cylinder need to retain pressure on the one side (unidirectional) of the cylinder due to the pressure acting from that direction. Whereas the seals for double-acting cylinders need to retain pressure from both sides (bi-directional).

Hydraulic cylinders are subjected to very high pressure and therefore it becomes very important to ensure the sealing of the system is extremely intact for the effective functioning of the cylinder and delivering the required pressure. Hydraulic cylinders function on the principle of reciprocating motion which necessitates the proper installation of piston seals for efficient operation. Various applications of hydraulic piston seals in the industry, and not limited to:

·Filtration Process – Seals have a vital role to play in Filtration process where two fluids are separated and seals are the one that keeps it separated from each other and resulting into the optimal performance of the system.

·Aerospace Industry – Hydraulic system installed in the aerospace industry focuses a lot on the efficient performing of equipment, where the selection of piston seals becomes extremely important.

·Fluid and Gas Handling Industry – Hydraulic fluid leakage continues to be a critical regulatory issue. Hence it becomes more important that the seals used for the hydraulic system are optimized for the hydraulic fluids in the future.

Factors to be considered while selecting the seals: 

Selecting a correct hydraulic seal for the required application is an important factor for its efficient functioning. Various steps required for the selection of seals are as below: 

Seal Function – Seal selection for rod, ram, gland, or piston may differ from one another. Therefore, the selection is carried out based on the type of sealing the seals are exposed to.

Sealing Method – Depending upon the application, the seals can be single, double, or multi-lips, complimenting the functioning of the system. 

Operational parameters – The range of pressure the seal is subjected to, in the system to ensure effective sealant formation even at the higher pressures.

Material Compatibility – Material compatibility of the seal with the system, is considered to be an important factor in determining the life cycle of the seal.

Operational Features – Unidirectional seals or bi-directional seals depending upon the functioning of the cylinder. 

Size of the seal – Required to be able to fit in the appropriate bore of the cylinder. Cylinders with larger bore correspond to the length of the cylinder. Accordingly, the seals are manufacture to fit in the larger bores.

General Instruction for proper installation:

·Make a designated working space for the installation of seals. Taking out hydraulic cylinders in an open and appropriate space provides the comfort of easy installation.

·Prior to installation of the new piston seal, make sure the old seal is removed without damaging the surface around the seal. With the help of seal pick, removal can be done quite easily.

·Cleaning the cylinder parts thoroughly to ensure no chips, dirt and other foreign particles remain in the groove of the cylinder. In addition to that, the cleaning of other parts will ensure the long-lasting performance of the seal to perform its function optimally.

·Prior to inserting seals in the grooves or tube, the sharp edges need to be debarred or chamfered to ensure smooth insertion of piston seal into the cylinder.

·Close inspection of the parts needs to be undertaken especially for the parts that require sealing for any scoring marks or cut. Scratches or scoring marks on the surface of cylinder parts can lead to damaging seals and thereby leading to the leakage in the system.

·Avoiding the installation of piston seals with sharp edges can go a long in ensuring the life of the seal remains intact. 

·Hydraulic piston seals are subjected to high pressure which mandates the proper seating of the seal in the groove of the cylinder. While installing the seal it is required to be ensured that the seal is seated into its position properly. 

·Use of designated lubricants or grease for the installation of seals on the cylinder. It is important to use the lubricants and grease compatible with the seals, or using the same lubricants used in producing the seals are recommended for installation.

·Not using any sharp-edged tools for the installation of the seals on the cylinder, as they could damage the seal while installing. It is recommended to use blunt and designated tools for the installation. There are tools available in the market specifically designed to install the seal on the cylinder.

·While installing the seals, it is to be ensured that the cylinder tube has a lead-in chamfer, if not there, then the installation sleeve is to be used for inserting seals.

·Post installation of the seals in its position, it is tested for the system leakage and confirmed for leakproof functioning prior to fitting into the system.

The above-mentioned instructions are the basic procedures and tips for the installation of hydraulic piston seals on the cylinder successfully. Though these seem to be very basic instructions for installation, it can lead to the effective installation of the seal. In addition to these instructions, the Manual, provided by seal manufacturers, includes the procedure for the installation of seals, which should also be read carefully to understand the basic procedure. Any doubt or clarity in the successful installation of the seal can be clarified by speaking to the OEM about the correct procedure to ensure a successful installation.