There are many different styles of hydraulic hose fittings. Each has its own benefits and drawbacks.
A few things to keep in mind when choosing a hydraulic hose fitting are versatility, reliability and port connections. To ensure the right fit, it is crucial to understand the various hydraulic hose fittings types.
Flare Fitting
Flare fittings are used for a wide variety of hydraulic applications. They are easily identified by their flared end that fits into a piece of tubing. Once the nut is tightened, it creates an effective metal-to-metal seal.
Flaring copper can be done manually or with pneumatic flaring tools, depending on the application. In some cases, flare fittings are used to join copper tube to iron pipe for water services or fuel gas (Liquefied Petroleum Gas / LPG), rather than soldering or brazing.
When selecting a flare fitting, it is important to determine the type of operation you need and what temperature range is required. Additionally, the pressure the hose will be exposed to should also be taken into consideration. Lastly, it is important to note whether the fitting is reusable or permanent (crimped). Reusable fittings require a wrench and vise, while permanent ones use a crimping tool. Both types are rated differently for maximum operating temperatures and pressure ratings.
Bite Type
Hydraulic hose fittings connect fluid systems to other components like hydraulic cylinders, pipes and tubes. They must be capable of creating a seal, even under high pressure.
Each fitting style has its own assembly requirements, and strict adherence to these steps is the difference between a leak-free connection and a problem waiting to happen. These connections may also require the use of special tools or machines to make them.
There are four common types of hydraulic hose fittings, and each type has a different way to attach a tube or hose to the fitting. These include crimp fittings that need to be crimped using a specialized tool or machine, JIC fittings that utilize a 37-degree mating surface, NPT pipe threads that are tapered and seal when interlocked with male and female styles, and bite type compression hydraulic hose fittings that are serrated inside and “bite” into the hose’s wire reinforcement for a stronger connection. Store Room Fasteners carries each of these styles of hydraulic hose fittings, along with the corresponding crimpers you need to complete your project.
NPT Pipe Thread
NPT pipe threads are common in fluid power systems. They have a tapered design that creates a leak-resistant connection by deforming the threads as they’re screwed together. The crests of the threads compress and displace material into the roots, creating an interference fit that prevents spiral leakage.
NPT threads must be lubricated with a liquid or Polytetrafluoroethylene (PTFE) tape to ensure a leak-free seal. The threads should also be inspected for burrs and nicks before use.
To determine the correct size of an NPT male or female fitting, you can use a caliper. Hold the caliper’s outside diameter (OD) part perpendicular to the threads for a male reading and its interior diameter (ID) part perpendicular to the female reading. Alternatively, you can use a seat angle gauge on the female threads to check the angle of the threaded surface. The right angle is important to prevent damage to the threads. If the gauge shows a 45-degree angle, it’s too steep and will not work correctly.
Four-Bolt Flange
Hydraulic fittings must connect hose segments and withstand high pressures. They also need to withstand shock, vibration and temperature cycles.
There are many types of hydraulic hose connectors, but two categories are particularly useful in hydraulic systems: fittings and flanges. Both provide a connection for pressurized fluid and help protect against contamination, but they differ significantly in how they accomplish these functions.
The main difference between these two is how they achieve a seal. Fittings use threading to tighten and connect, while flanges use a set of flat surfaces to bolt together.
Flare fittings use a flared or coned end on the body of the fitting to create a deep seal against a flared hose end. They’re used for thin- to medium-walled hoses and can handle higher pressures than standard compression fittings. Crimp fittings involve placing a hose on a tubular end and crimping it against a sleeve, ring or crimp socket. These types of fittings require crimping tools or machines to connect.
