Parker Hannifin: Fittings 101

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Parker Hannifin plated brass and steel fittings have been recognized as the best in the industry for more than 50 years because of their durability and corrosion fighting qualities – but the dizzying array of choices available can bewilder those unfamiliar with terms like Ferulok, O-ring face seal and Jic tube.

Parker addresses this problem by offering a FittingFinder app that can be downloaded for Apple or Android devices, but this article is designed to delve a little deeper and go over the basics of Parker fittings.

The primary role of Parker hose fittings is to ensure that hydraulic system connections remain leak-free and stable, and there is a wide variety of different styles and types of fitting to choose from. When deciding which of them is most appropriate for a given application, the acronym STAMP can be very a useful tool. STAMP stands for size, temperature, application, media and pressure.

Size

To determine the correct size for Parker fittings, hose assemblies should be checked and the wall thickness and outside diameter of the tube measured. This is because most hydraulic connectors have tube wall limits. Generally speaking, flared fittings are able to deal with thicker tube walls than flareless connectors.

Temperature

The temperature ranges that Parker hydraulic fittings can endure are based on the materials they are made out of and plated with and the type of seals, if any, they use.

One of the reasons that Parker Hannifin remains so far ahead of its competition is their state-of-the-art metallurgical lab that is designed to replicate the conditions fittings are used in.

O-ring seals are the most popular option when preventing leaks is a priority, but metal-to-metal seals may be a more prudent choice when higher temperatures are likely to be encountered. Fittings made of aluminum or brass are suitable for use in temperatures from minus 40 degrees Fahrenheit to 400 degrees Fahrenheit. At the other end of the scale, stainless steel fittings can handle temperatures as low as minus 425 degrees Fahrenheit and as high as 1,200 degrees Fahrenheit.

Application

The environment in which hose fittings will be used also influences type and design choices, and fittings with protective coatings are recommended when exposure to corrosive elements is anticipated.

Electroplated zinc is the most common way of protecting steel fittings as it is a sacrificial metal, which means that it corrodes to prevent other metals from corroding when oxygen and moisture are present. When conditions are especially toxic, corrosion resistant brass or stainless steel provide even greater protection.

Parker also plates fittings in zinc nickel for use in situations where hydraulic connections are likely to be exposed to detergents, salt or fertilizer. The most durable fittings of all feature Parker’s ToughShield plating, which can resist rust for as long as 1,000 hours during grueling ASTM salt spray tests.

Media

The type of fluid that will be traveling through hydraulic hoses is another factor to consider when choosing fittings and seals. To make this task less challenging, Parker has drawn up a Fluid Compatibility Chart that matches dozens of fluids with brass, steel and stainless steel Parker hydraulic fittings featuring seals made out of BUNA-N synthetic rubber, fluorocarbon, neoprene and ethylene propylene.

Pressure

There are two types of hydraulic systems in use today. Static systems are not designed to withstand more than 30,000 operating cycles and are suitable only for applications that will not expose them to pressure, shocks or vibrations. Dynamic systems are far more robust and can exceed a million operating cycles without failing.

This is important because the dynamic pressure rating of Parker hose fittings should be at least as high as the pressure developed by the system they will be used on. This is where design factor comes into play. This compares the strength of the material used with the pressure rating of the connection.

Normal conditions call for a 4:1 design factor, severe conditions warrant a design factor of 6:1 and fittings used in hazardous situations should have a design factor of 8:1.