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Brake hose pressure testing

Roadjunkie1

Roadjunkie1

Well Known Member
I am in the mood to test my brake lines. I have seen posts to test them to the maximum pressure tolerance of the hose but this seems excessive as the brakes will likely never produce this pressure. What pressure should brake lines be tested to? I have a hydraulic cylinder that will produce enough pressure to lift a Jet Ranger helicopter so should produce enough to test the lines.
 
Brake line pressure

Mikeyb said:
For Matco brakes the operating pressure is listed as 450 psi
https://static.veracart.com/matco/item_pdfs/3648/document1.pdf
Click to expand...

Thanks! The accompanying paper and diagrams are pretty informative as well. Testing them to 1000 psi should be sufficient. Looks like a trip down to my favorite hydraulic hose dealer is in order. I hear they do not charge much to pressure-test them and that would save me from making up a system to test them myself; they already have a system!:)
 
Isn't the brake line on the low pressure side of the system?

In A&P school our instructor fabricated a hose assbly as a demonstration and then tested it. When he got to 1000lbs the fitting blew off and sent hydraulic fluid 50 ft in the air.
 
Brake pressures

rmarshall234 said:
Isn't the brake line on the low pressure side of the system?

In A&P school our instructor fabricated a hose assbly as a demonstration and then tested it. When he got to 1000lbs the fitting blew off and sent hydraulic fluid 50 ft in the air.
Click to expand...

I'd like to have seen THAT!

The lines from the reservoir to the master cylinders are low pressure. From the masters to the slaves (calipers) is the high-pressure side. That's what makes us stop. The paper quoted in post #2 states that 450 psi will get the aircraft slowing down. I was taught that the test of any hose is to take it to twice what the maximum expected pressure would be. That would be roughly 1000psi for a brake line. Tom puts their (very good) hoses to the test! Fuel lines: 20. Oil: 200. Taking it higher would give you more confidence it was not going to fail but......:confused:
 
Robert, LOL---Yep if you dont do it correctly, you have enough pressure, and no containment, it can make a mess--AND create a projectile.
I created a stir many years ago when I stated that I was doing integration testing of hose and hose end stem design at 7500 psi. Guys thought I was nuts. But, sometimes you just have to know. (Actually for -3 and -4 I used to go to 9900 which was the limit I could get back then.) So, if you can make the assembly hold together at those high pressures, then certainly there is no issue at the low pressures we use. WE use 2000 as our test point for assemblies -2 through -8, then 1000 for our -10 through -16 convoluted hoses. Wayy above they actually see in real life. The integration test point for the -10 hoses that some of you have for inverted oil systems was 4500 psi. LOL good thing I have a GREAT cabinet--hose end blow off at 5500 sounds cool, but the mess----but you just gotta know!!!

Tom
 
Yes, all of us students got a really good laugh out of that one when it happened. There was a small plastic containment shield but it was homemade and totally inadequate. The instructor got douched and the hose straightened vertically sending most of the oil skyward. It was a good visual demonstration, I was smart enough to be in the back row. Hahaha.

I should have been more clear...
Isn't the really high pressure developed in the caliper with the large pistons? I wonder how much pressure the small master cylinders generate?
 
rmarshall234 said:
I should have been more clear...
Isn't the really high pressure developed in the caliper with the large pistons? I wonder how much pressure the small master cylinders generate?
Click to expand...

It is a closed system and therefore the pressure is constant throughout the system.
 
Don’t underestimate the braking force required to stop an RV. An 1800 lb RV8 at 60 mph has a kinetic energy of 218,000 ft lb. It’s near the limit of the 5” Matco brakes of 230,000 ft lb. With 450 psi of pressure supplied to the calipers the brake is producing 166 ft lb of torque on each wheel!
 
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