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HYDRAULICS HOSE & COUPLING EDUCATION
Hydraulics
hose & couplings
INTRODUCTION This book was created to help those who have limited knowledge of hydraulics. It should give you a general knowledge level that allows you to communicate with your customers and provide them with the products that they need to keep their equipment in running order.
Some of the factors that should be considered when choosing which products to use in a hose assembly are: • • •
Pressure of the system The chemical composition of the fluid or gas The temperature of the fluid or gas
There are external conditions that may affect which hose to use such as: • • •
Abrasive environments Confined areas that require a tighter bend radius than normal Extreme ambient temperatures
Select the hose type and size that you need. Some factors to consider when choosing the hose are: • • •
Operating pressure of the system The chemical makeup of the fluid or gas that you are transmitting The port sizes on the equipment that you are connecting to.
After choosing the hose, then select the couplings: • •
The type of hose dictates what series of couplings to use After selecting the series, then match the port connections on the equipment
This book should help to clarify the factors that need to be considered when servicing your customers hydraulics needs.
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Hydraulics
hose & couplings
COUPLING EDUCATION When choosing couplings for a hose assembly, the hose type dictates which type of coupling should be used. For hydraulic hose assemblies, there are two basic types of couplings: Field Attachable and Permanent Crimp fittings.
Field Attachable vs. Permanent Crimp Couplings Field Attachable • •
No special tools are required for installation Compression of the hose against the coupling stem holds the hose in place
Field Attachable Couplings
There are two types of field attachable couplings: PUSH-ON and SCREW-ON. Both types are re-usable, if the hose needs to be replaced
Push-On Couplings
These couplings are the easiest to install, and require no tools. Simply lubricate the barbed end, then push it on the hose. Push-on couplings may be differentiated from other barb type fittings by the yellow plastic ring on the barbed end of the fitting. They are for use on Weatherhead’s low pressure shop air hose (H201 series) and Gates LOL series hose. The use of hose clamps with these couplings is NOT recommended, as the barbs are sharp, and may cut through the hose.
Screw-On Couplings
Screw-on couplings consist of two pieces, a stem and ferrule. While screw-on couplings may be used with some 1 and 2 wire hose, they are only required to be used on hose that has textile braided covers. This hose is generally used in fleet applications. These couplings do not require a crimper to install. Simply screw the ferrule on to the outside of the hose, then install the stem by screwing it into the inside of the hose. The coupling is retained by expanding the hose out against the ferrule.
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Hydraulics
hose & couplings Permanent Crimp • • • •
Generally used for medium to extremely high pressure applications The couplings are NOT re-usable A crimper is required for assembly The crimper compresses the ferrule, causing the hose to be trapped between the ferrule and the stem of the coupling.
Permanent Crimp Couplings
As their name indicates, these couplings are NOT re-usable, and a crimper must be used to attach the coupling to the hose. They tend to be used on higher pressure hose assemblies. For both Weatherhead and Gates, there are different series of crimp couplings used depending on the type of hose that is being used. In the Fastserv catalog, the hose section spells out what series of couplings to use for each type of hose, and the coupling section spells out which hose to use.
Weatherhead Permanent Couplings
There are 3 series of couplings, all are one-piece construction.
Coll-O-Crimp U series
Used for 1 and 2 wire braided hose that requires a permanent coupling to be used.
Coll-O-Crimp E series
Used with the H436 line of hose and they may be used with the H009 series of hose.
Collo-Crimp 430U series
Used for 4 and 6 wire spiral hose. Skiving is not required for this hose.
Gates Permanent Couplings
Gates uses 3 series of permanent couplings:
MegaCrimp series
Used for 1 and 2 wire braided hose applications where a permanent coupling is specified. The MegaCrimp series couplings are a 1 piece design.
Global Spiral series
These couplings are used with 4 and 6 wire hose up to 1-1/4” diameter. The Global Spiral series of couplings are a 2 piece design, consisting of a stem and a ferrule When installing the coupling on the hose, the Ferrule is slipped on the outside of the hose and the Stem is inserted inside the hose, then crimped.
PCS series
These couplings are only used on 1-1/2” and 2” spiral reinforced hose. They are installed in the same manner as the Global Spiral couplings, except that the hose must be skived prior to the fitting installation. Fastserv does not currently stock these fittings.
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Hydraulics
hose & couplings Coupling Port Connectors The coupling port connection is where the hose assembly attaches to the equipment. Naturally, the equipment dictates what the end connection will be. There are many different attachment methods, the following will explain the most common types:
There are 4 basic types of hose to equipment connections: • • • •
Thread Interference O-Ring Mated Angle or Mechanical Joint Mated Angle with O-Ring
Thread Interference
The main characteristic of this type of coupling is that the threads are tapered, the starting diameter is smaller at the end and gets larger at the hose end. The seal is achieved when the threads distort and flatten out and the threads seal against one another. There are two thread types of thread interference:
NPTF: National Pipe Tapered Thread Fuel
Contrary to popular belief, tapered thread fittings should be replaced whenever the connection is taken apart.
BSPT: British Standard Pipe Thread
O-Ring
The o-ring does all of the sealing in this type of end. There are three types of o-ring fittings:
Flange type
As its name indicates, the flange type has a square 2-piece flange with a bolt hole on each corner of the flange. The o-ring resides in a grove in the couplings flat face.
Male Boss type
This coupling is a straight thread fitting with an o-ring placed at the hex head of the male fitting. The female side of the fitting is usually a port on the machinery that the fitting attaches to.
Flat Face type
This coupling resembles a pipe thread fitting, but it has straight (not tapered) threads and a groove is machined in the male end of the fitting. The coupling is tightened until it bottoms out, with the compression of the o-ring making the seal.
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Hydraulics
hose & couplings Mated Angle or Mechanical Joint
The style of seal is usually a flare type. The following is a list of some of the types:
JIC 37 Degree Flare
The 37 degree flare is most commonly used on high pressure hydraulic tubing. Care must be taken to not confuse JIC fittings with SAE 45 degree fittings.
SAE 45 Degree Flare
This fitting is generally used on low pressure applications, usually with soft copper tubing. Common applications are fuel lines and refrigeration tubing. The JIC and SAE flares look very much alike, and some sizes have the same threads, care must be taken when determining which type to use. Fastserv has gauges available to help identify these fittings.
Mated Angle with O-Ring
This coupling is a cross between a flare fitting and a O-Ring fitting, they are available in BSPP British Standard Pipe Parallel or DIN 24 degree cone types.
COUPLING ID AND MEASUREMENT Identifying what type and size of a coupling that you are looking at is not a difficult process; you just need to understand the basics. The following should assist you. We will look at each type of coupling and explain how to determine the type and size. It’s highly recommended that you obtain a coupling and fitting ID kit (Fastserv part # F78450). This kit contains a pocket caliper, thread pitch gauges, seat angle gauges and a helpful book explaining the identification of fittings and couplings. This kit will be very useful for identifying Inch couplings and fittings; it can also be used for basic identification of Metric and Whitworth type fittings. The hose type and size is the first determining factor when considering what coupling to use, so this measurement should be taken first. The hose inside diameter dictates its size and the inside tube of the coupling should match the ID of the hose. The ‘dash size’ is always marked on the cover of the hose; however, on old, dirty hose it may not be visible. For field attachable couplings, the diameter of the tube will be slightly larger than the actual hose size, as the hose is stretched slightly over the tube. The hose side of a coupling is sized by the inch, but the port side of couplings can be one of three basic standards: INCH, METRIC or BSP (Whitworth). In this section, we will explain how to identify and measure each type. After determining the basic type of coupling that is being used, the next measurement should be the thread size and pitch on the port side of the coupling. The applicable dimensions are listed in the Fastserv catalog (if Fastserv carries the coupling), in the coupling manufacturers catalog or in the pamphlet located in the coupling and fitting ID kit. Both brands of hydraulics that Fastserv carries (Weatherhead and Gates) have their part numbers stamped on the coupling, this is obviously the easiest method of identifying a coupling if you are looking at one of their parts.
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hose & couplings INCH COUPLING IDENTIFICATION NPT COUPLINGS
There are two basic types of NPT couplings: NPTF (National Pipe Tapered Fuel) and NPSM (National Pipe Straight Mechanical). As the name indicates, the tapered threads on the NPTF fitting seal by thread interference and the NPSM fittings use a tapered mechanical seal.
NPTF Couplings
This coupling has tapered threads. Measure the diameter of the end of the threads to determine the port size of this coupling.
NPSM Couplings
This coupling has straight threads; the sealing is done by a 30 degree tapered seat. These couplings are not common. Fastserv does not curently stock them.
FLARE COUPLINGS
On the inch sizes, there are two types of flare fittings: SAE 45 degree and JIC 37 degree. The difference between the two is the degree of the angled seating surface. Weatherhead features a ‘Dual Pattern’ seating surface on all but their 3/8” and 3/4” sizes. The swivel nuts are different sizes, and the couplings are NOT interchangeable. For the other sizes, the same female coupling can be used, whether the male is JIC or SAE. The male half of the flare assembly is NOT interchangeable. Center Lines Center Lines Are Parallel
NOTE: Gates does not offer this feature.
At An Angle
CHECKING THE FLARE ANGLE
The best way to check the angle is to use the gauges that are included in the coupling and fitting ID kit. To check for the correct angle, place the tool against the angled seat, if the angle is correct, the tool will be parallel to the fitting port. If it is not parallel, place the other end of the tool in position to check for the correct angle.
Right
Wrong
MALE BOSS O-RING COUPLINGS
This coupling is easily identified by its o-ring around the base of the male fitting. It is measured by checking the outside thread diameter and the pitch of the threads.
Thread OD
O-Ring Boss Male (MB)
O-RING FACE SEAL
This coupling is identified by its o-ring contained in a groove machined in the face of the male half. It is measured by the same method as the Male Boss coupling.
4 BOLT FLANGE COUPLINGS
These couplings are common on heavy equipment; they are often referred to as SAE J518 series. They are secured by a 2-piece split flange, with a bolt at each corner. There are three types of these couplings: code 61, code 62 and Caterpillar style. They are all of the same basic design, except the code 62 has a larger diameter and thicker flange than the code 61 series. The Caterpillar flange is the same diameter as the Code 62, but its flange is thicker yet. The code 61 series is the most common of the three. These couplings can be measured by the flange diameter, the flange thickness (at the port) and the port inside diameter of the coupling.
Code 61
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Code 62
Caterpillar Style
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Hydraulics
hose & couplings METRIC COUPLING IDENTIFICATION Metric couplings are a bit more challenging than their inch counterparts, due to their many variations. They are measured by the same means as the inch couplings, except of course the dimensions are metric. The metric couplings still use inch sized hose; the only difference is in the port dimensions. On Weatherhead couplings, the tube, inner hex and sealing surfaces are finished in a darker zinc finish than the rest of the coupling. This makes the determination of their metric size much easier. NOTE: If your customers have Metric and/or BSP couplings, it is advisable to purchase the metric thread identification kit (Fastserv part # F78467).
30 DEGREE FLARE COUPLINGS
For Asian metric sized fittings, the common flare angle is 30 degrees. There are 2 types of 30 degree couplings: the Japanese and Komatsu styles. The actual flare angles are identical; the only difference is in the threads. The best way to check the angle is to use the gauges that are included in the coupling and fitting ID kit. To check for the correct angle, place the tool against the angled seat, if the angle is correct, the tool will be parallel to the fitting port. If it is not parallel, place the other end of the tool in position to check for the correct angle.
Thread ID 30O
Japanese 30O Flare Female
The best method to tell if the coupling is Japanese or Komatsu style is to check the hex sizes on the coupling. The Komatsu coupling actually uses INCH sizes, while the Japanese style uses METRIC size wrenches on the hex. The thread size and pitch can also be used for verification. On Gates Komatsu style couplings, the outer hex has 2 grooves machined on each point of the hex to assist in identification.
24 DEGREE DIN COUPLINGS
The 24 degree Din coupling is easily identified by Its counterbore on the male half, and its 24 degree cone. Most female versions have an o-ring on the cone. Use the 12 degree angle gauge to measure the cone, as the 24 degree figure is the total angle (both sides), not one side of the seat.
24O
Tube OD
ThreadOD
12O
Male 24 Cone, DIN 2353 (MDL/MDH O
Thread ID
Female 24O Cone with O-Ring (FDLORX/FDHORX)
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Hydraulics
hose & couplings BSP COUPLING IDENTIFICATION British Standard Pipe couplings are different from Metric or Inch couplings, as they are the only type to use Whitworth threads. These couplings are very similar in appearance to NPT couplings. NOTE: If your customers have Metric and/or BSP couplings, it is advisable to purchase the metric thread identification kit (Fastserv part # F78467). There are three types of BSP couplings:
BSPP - British Standard Pipe Parallel
This coupling type is similar to the NPSM style, but the thread pitch and seat angle is slightly different.
Thread ID 30
O
FBSPORX
55O
BSPT - British Standard Pipe Tapered
As with the BSPP coupling, the BSPT coupling is similar to the NPT coupling, but it has an inverted flare and slightly different pitch and thread counts.
Thread OD
BSPT Male (MBSPT)
Thead ID
BFFS - British Flat Face Seal
This coupling style is very similar in appearance to the inch Flat Face O-Ring design; the difference is in the thread pitch and count. Female British Flat-Face (FBFF)
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Hydraulics
hose & couplings HOSE EDUCATION A typical hydraulic hose has 3 components:
The Tube
This is the inner sleeve that the fluid or gas flows through. The material that the tube is made of depends on the medium that it is being transported through it. Three common materials that tube is made of are: Neoprene, Nitrile and Synthetic Rubber.
The Reinforcement
The reinforcement supports the tube, keeping the expansion of the tube controlled under pressure. There are 2 basic types of reinforcement, Braided (steel or fiber) and Spiral. The type of reinforcement that is used depends on the working pressure of the hose. As a general rule, braided reinforcement is used when working pressures are under 4,000 psi; spiral wrapped reinforcement is used when the working pressure is 4,000 psi or more. When referring to what type of hose is being used, the terms 1 wire, 2 wire, 4 wire or 6 wire are commonly used. One and 2 wire hose has braided reinforcement, while 4 and 6 wire hose has Spiral wrapped reinforcement.
The Cover
Braided
Spiral
The cover’s purpose is to protect the reinforcement and tube from the elements on the outside of the hose. Abrasion and chemical resistance are two of the major attributes of the cover on a hose assembly. Most hose manufacturers make hoses with extra tough covers for severe environments. The cover is usually composed of a fabric braid or synthetic rubber. The fabric cover allows trapped gasses to safely vent from the hose, while the rubber cover is much more abrasion resistant.
Hose Specifications Sizing
Hose is always sized by the Inside Diameter (ID). Its size is usually specified as a ‘dash’ size. It is usually measured in 1/16’s of an inch, for example a 1/2” ID hose is referred to as a -8 hose. A 1-1/4” hose would be referred to as a -20 hose. There are a few exceptions to this rule. In Fastserv’s product line, the hoses that have fabric covers are designed to be used with tubing instead of pipe. Tubing is sized by its outside diameter; while pipe is sized by its inside diameter. Therefore, a -4 fabric covered hose is actually 3/16” ID since the OD of 1/4” tubing is actually 1/4”.
Bend Radius
This term is a measurement of how far a hose can be bent before exceeding its design parameters. It is measured from the start of the arc to the finish, it is measured in inches. Hoses with heavier covers tend to have a larger bend radius, due to their stiffness. Exceeding the minimum bend radius rating of a hose can be hazardous, and will significantly affect its service life.
Working Pressure
This is pressure range that the hose was designed to be used under. The normal system pressure (including pressure spikes) should fall within this range.
Minimum Burst Pressure
This parameter should not be used in the selection of hose. The hose will withstand pressure spikes to this point, and should never be considered a working pressure rating. Any hose subjected to pressures higher than the working pressure range will experience significantly lower service life.
Temperature Range
This is the temperature range that the hose was designed to operate under. Any exposure to temperatures higher or lower will significantly affect the performance and life of the hose assembly. Factors such as bend radius will also be affected by temperature extremes.
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Hydraulics
hose & couplings Testing Agency Specifications
There are numerous agencies who publish industry wide parameters for manufacturers to follow; some examples are: Society of Automotive Engineers (SAE) Department of Transportation (DOT) Underwriters Laboratories (UL) Mine Safety & Health Administration (MSHA) European Normes (EN) Deutsche Industrie Norme (DIN) American National Standards Institute (ANSI) U.S. Coast Guard (USCG) The standards that each series of hose meets will be listed in the Fastserv catalog.
Selecting The Right Hose For The Job
Gates suggests using “STAMPED”, a simple way to remember the necessary parameters when selecting hose. S T A M P E D
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Size Temperature Application Material to be conveyed Pressure Ends or couplings Delivery (volume or velocity)
SIZE
The size of the hose should be visible on the hose; if it is not, cut the used hose somewhere in the middle and measure the inside diameter.
TEMPERATURE
The minimum and maximum temperatures of the fluid or gas being conveyed in the hose must be within the temperature range specified by the hose manufacturer. Any temperatures outside the specified range will reduce the service life of the hose. High ambient temperatures may need to be addressed by installing a heat shield to protect the hose.
APPLICATION
Some of the issues that should be considered are: • Vibration • Mechanical Shock • Fire and or sparks • Abrasion • Bend Radius If one or more of the situations are present, we may stock a hose that will deal with it better than a standard hose.
MATERIAL
The material that is to be conveyed should be taken into consideration. (ie: some hose is not designed to move petroleum products.)
PRESSURE
The system pressure must always be within the working pressure of the hose. Any pressures exceeding the published working pressure of the hose will significantly reduce the service life of the hose and can constitute a dangerous situation.
ENDS (or couplings)
When building a hose assembly, you should choose the hose type which meets the systems requirements first, then choose which type of coupling is needed for the hose. After the type of coupling is determined, the proper port connection should be decided.
DELIVERY
If a hose assembly is being replaced and the hose diameter matches the original hose, then the system should operate as before. If the system is new or altered, the proper diameter of hose and fittings must be selected for proper system operation.
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