How to identify hydraulic hose

This information covers high-pressure hydraulic hose for systems such as industrial machines, marine applications, tractors, excavators, presses and pressure hoses etc.

You should always keep a record of the following information along with a schedule for when each hose is due to be replaced. This will ensure easy maintenance and replacement of your hoses.

Modern hoses are clearly marked with the hose type, size, pressure rating and cure date. Do not rely on this information if you think the system pressure may be greater but also never fit a new hose that is rated with a lower size or pressure.

Each hose on a system may have a different rating so make sure you check each one. Some will be high flow and high pressure while other parts of the circuit may require lower flow and lower working pressures. Remember that cylinder intensification can result in pressure higher than the pump setting.

Include the manufacturer markings in the comments box if no standard or codes are provided.

It's good practice to write an item number on each hose and mark where both fittings are connected so that you will have no difficulty identifying where to fit the new hose later.

The item number step size can be increased within the register by and pressing 'CTRL+' or 'CTRL-'.

Measure and specify the ID, not the OD. For example 3/4'' is the hose bore size, not the outside diameter. Because of different wall thicknesses, you cannot rely on measuring the outside diameter of a hose.

If the hose is not marked then the most reliable method of checking its size is to measure ferrule outside diameter. This will vary for each hose and ferrule type but we quote common sizes in our program data and this measurement, although only approximate, will give an indication.

Hydraulic hoses are rated for different pressures, temperatures, fluids and/or environments. This often depends on the number of internal wire braids, the rubber used and ferrule or end fittings etc. For example, R2T hose has 2 wire braids and is commonly used for low to medium pressure hydraulic fluid. 4SP hose has 4 wire braids in within the rubber and is capable of higher pressures.

Without cutting the hose you will not be able to see how many wire braids are used within the hose.

Many ferrules have small external grooves to indicate what the hose type is and ensure they are not used on the wrong hose.

2 wire braid R2T hose will have 2 grooves and 4SP 4 wire multi-spiral has four groves.

You may also see three grooves which indicates a 2 wire hose but with skived ends. Or 6 groves which indicates 4 wire hose with internal and external skives.

Stainless steel fittings are common in many marine or high-quality applications however the fitting appearance, design and sizes will vary slightly from the standard plated fittings quoted in our data.

Skiving is when the external or internal rubber is removed to expose the wire braiding. This is only done for the length of the ferrule and allows the ferrule to locate more securely on the wire braid.

Each country or industry can have its own standard fittings. However, there is rarely a set standard and equipment fitted to the same machine can often have different standards.

In the UK, BSP 60 cone are common. These often have a distinctive rounded nut. If the nut flat faces continue full width and is fitted to metal tube then it's probably metric. If the nut has 2 notches in then it's probably JIC 37 degree flare. You will need to break each fitting to make sure whether it's coned or a flat face seal. However, you must always make sure the power is off, load is supported and pressure released before loosening any fittings. The best way to check is to measure the taper angle or screw a known fitting into the hose. You can also check thread pitch and diameters to confirm things.

In summary, you will need to:-

• Identify whether they are male or female threaded fittings
• Identify the thread as BSP, Metric or JIC flare etc.
• Identify the thread size. If in doubt then measure the OD (male) ID (female) of the thread and the pitch.

Every fitting must have a metal and/or rubber seal.

Flared fittings seal on the cone. Both faces having the same metal flare angle, one may have an O-ring as well.

Flat face fittings will require a Dowty seal if they do not already have an encapsulated face seal. Metal to metal flat face seal will not be leak free without a rubber seal whereas coned face seals should be leak-free. Cleanliness and damage free surfaces are vital for maintaining leak free operation.

If you have two elbows, one on each end of the hose, then you must specify the relative angle of end one compared to end two.

To specify this hold the hose ends in your right and left hands. Bring your right hand towards you and move the left away. Now looking straight down the hose rotate the right hand clockwise to give the relative angle of one fitting to the other.

Be careful that you have sufficient swivel fittings to align the hose and/or any fittings or valves etc.

Hose fittings are generally plated steel but often for marine applications will be Stainless Steel. Always use a lubricating paste to on stainless threads to stop them binding when you assemble them. If hoses are on a boat's deck, or similar marine environment then we recommend Denso tape is used to protect them.

Keep a list of all new hoses including the material cure date. This will make replacement much easier and avoid the danger of out of date hose failures.