Heads Up for Hosers: Medium Pressure Hose

Welcome back to Gear Up with Gregg’s! In this Heads up for Hosers blog, we’re going to show you that there’s no reason to be bent out of shape about finding the correct medium-pressure hydraulic hose for your application.

In the early 1940s, heavy-duty trucks and vehicle fleets relied on metal tubing for their hydraulic systems. This is because there were no flexible hoses on the market that were designed specifically for use in the heavy-duty trucking industry. However, mechanics discovered a heavy hose with a high working pressure, which was originally used for the hydraulic lines of aircrafts, and applied it to their vehicles. Soon, this type of hose replaced the rigid metal tubing in fleet trucks.

But why did hydraulic hose replace metal tubing?

The answer is simple - bend. Medium-pressure hydraulic hose had the bend radius, and the ability to handle the necessary PSI, a measure of pressure in pounds per square inch, to stand up to the task, while metal tubing was too stiff and difficult to bend in tight confines.

Bend Radius

Medium Pressure Hose | Gear Up With Gregg's Blog

Bend radius is the minimum radius you can bend a pipe, tube, cable, or hose without kinking it, damaging it, or otherwise shortening its life. Metal tubing’s bend radius, depending on the size and type of tube, is typically between 230 mm to 20 mm, while medium-pressure hydraulic hose ranges from 152 mm to 5 mm—and those millimeters can mean a big difference in a system where space is tight!

Operating Pressure

Operating pressure for medium-pressure hose generally ranges from 500 PSI to 3,700 PSI and can be easily located on the hose’s lay line. The larger the I.D. of a hose, the larger the bend radius tends to be.

Material

The material used to make a hose can also affect its bend radius. Hoses are made up of three parts— an inner tube, a reinforcement layer, and a protective outer layer. The inner tube is typically made of nylon, polyester, or synthetic rubber, while the outer layer is made of polyurethane or synthetic rubber. Since these materials don’t vary much from one medium-pressure hose to another, the difference in bend radius is determined by the reinforcement layer.

Reinforcement Layer

The reinforcement layer in a medium-pressure hose can either be a spiral design, fiber braid, or a one or two-wire metal braid. The more layers of reinforcement, the less a hose will bend. Also, textile braids will typically provide a smaller bend radius than wire braids, but also offers a lower PSI rating.

Now, medium-pressure hose is typically used for general hydraulics, chemical transfer, and mobile equipment (such as forklifts, pickers, and utility vehicles) but it can even be used for things like rescue devices and tools!

Let’s go back to the forklift for a second. Forklifts are a great example of how medium-pressure hose can maintain a hydraulic system in tight spaces.

All those twists and bends, would be difficult to accomplish with metal tubing alone. Not to mention the forks! The forks are powered by the hydraulic system, just like the steering is but… unlike the steering, the hoses attached to the forks need to have more room to flex and move, and to handle the vibration and variance of driving with a load.

Examples of Medium-pressure Hose

Let’s take a look at some specific examples of medium-pressure hose to get a better idea of the right applications;

3TR7 Synflex

The 3TR7 Synflex hose is used for general hydraulics, forklift, high-pressure gas transfer, and chemical transfer. It can operate in temperatures ranging from -40°C to 100°C (or up to 66°C if it’s carrying water-based or fire-resistant fluids). The maximum operating pressure ranges from 1,000 to 3,050 PSI. With a braided synthetic fiber reinforcement layer, this hoses’ bend radius is between 13mm and 190 mm, depending on the hose ID, or internal diameter. That makes it perfect for those hydraulic systems without a lot of space to spare.

Aeroquip 1503 Hose

Now, if you’re looking for something with a bit more structural strength, the Aeroquip 1503 Hose is just what you need. This hose is used for hydraulics, air, gasoline, crude oil, fuel, and lubricating oils. Ranging from 350 to 3000 PSI, the 1503 hose has both a textile inner braid and a single wire braid reinforcement layer. Great for temperatures between -40°C to 121°C, and with a bend radius between 76.2 mm and 610 mm, this hose is sure to get the job done. It’s also D.O.T. approved for air brake applications.

Here at Gregg’s, we’ve got medium-pressure hose for any application. Whether it be the transportation of oil, fuel, air, water, or chemicals, our professionals in the hose shop can do it all. So, if you have any questions feel free to give us a call or you can check out our YouTube channel, where we have lots of Heads Up for Hosers videos! Thanks for checking in with Gear Up with Gregg’s!