The components in the fluid system are held together by a variety of couplings and fittings. These standard connections can be used in various combinations to meet almost any plumbing requirement. Some of the plumbing solutions found in the industry are unique.
Most of the fittings listed here are available in standard SAE sizes including 1/8", ¼", 3/8", ½", ¾" and 1". Depending on the fitting, other sizes may be available as well.

Most of the fittings used in the industry are made of brass, but other materials ranging from steel to pvc may be used for fittings. The pressure and temperature handled by the fitting gives you an indication of what type of fitting can be used in a specific installation.

Common fitting types include:
Nipple - a section of pipe threaded on both ends. A nipple may be an inch or more in length, depending on the distance, which must be spanned. Nipples may be custom-made for specific installations and may not be a standard length.
Close Nipple – a short section of pipe threaded on both ends with the threads meeting in the center.

Hex Nipple – a close nipple with a hex-shaped portion in the center to allow a wrench to grip the fitting to ease removal.
Coupling – a connector with female threaded ports on each end. Other pipefittings with male threads may be screwed into either or both ends.
Hex Coupling – a coupling with a hexagonal section into the center to allow the coupling to be gripped with a wrench.
Bushing – fitting with an exterior male thread on one end and a smaller female port on the other.
Tee – three-way fitting with a female port on each end and a third female port in the center.
Cross – a four-way fitting with female ports set in 90-degree opposition to each other.
Hose Barb – allows connecting a low-pressure hose to a threaded fitting. The barb has a ribbed, somewhat conical barb on one end and a male thread on the other. Hose barbs are available with a female port as well. Hose barbs are specified by thread and hose barb size. A ¾ x 3/8 hose barb designates a ¾" thread and a hose barb for a 3/8" ID hose.
Eli – a 90-degree female threaded fitting allowing connection of two male fittings at a 90-degree angle to each other.
Elbow or 45 Degree – a 45-degree female threaded fitting.
Jig Fitting – beveled on the connection end. Teflon tape or pipe joint compound is not required to make a watertight seal. When the fitting is tightened, pressure against the bevel seals against leaks.
Union – allows connection and disconnection of pipe supply lines without the need for plumbing alterations.

Quick Connects
Inlet and outlet fittings, spray nozzles, lances, trigger guns, pressure gauges, down-stream injectors and other devices may make use of quick connects, allowing easy connection for hoses, guns, nozzles, lances and accessories. Quick connects at the gun and nozzle allow for easy switching of wand lengths and accessories.

Check For Proper Locking

Whenever a quick connect is used to make a nozzle or device change, especially on the high pressure side of the system, check to see that the locking ring has snapped forward to the locked position. If the ring has not fully returned to the locked position, the nozzle will be shot out of the lance by water force as soon as the trigger is depressed.

When using a quick connect, make certain the locking ring has returned to the locked position.

When a cleaner is operated with the nozzle removed, the 0-ring may be flushed out of the quick connect socket. If this happens, when the nozzle is replaced water will squirt out of the connection around the balls in the quick connect. The 0-ring should be reinserted in the quick connect socket and the plug reconnected properly.

Types of Quick Connects

There are four basic types of quick connects with which you may come in contact:
- High-pressure straight through connectors. These are the most common, especially on United States-manufactured equipment. These connectors include the Parker BST Series as well as Foster Manufacturing and J.E. Adams styles. With the ring on the socket pulled back the plug slides in easily and automatically locks when the ring is released. To remove the plug, slide the ring back again and the plug can be removed.
– Straight through connectors for garden hose. These are similar to their high-pressure cousins but will only have three or four locking balls rather than the eight or more generally found on the high-pressure connectors. With less pressure to retain, the need for retaining strength is lessened and fewer locking balls are required. These types of connectors are manufactured by Rain Bird and various European manufacturers.
– Twist connectors. These are most often found on European cleaners. The connector is fitted with a knurled grip on the socket, which simply screws on the plug by hand. When the plug is screwed all the way in, an O-ring is compressed and the connection is sealed.
– Shut-off connectors. These close or shut off when the plug is removed. They are generally used with air systems and should not be used on high-pressure cleaners. These are most often installed by inexperienced operators replacing defective connectors.

WARNING: Should shutoff connectors be installed on a cleaner, there may be pressure trapped in the system. Extreme caution should be used when replacing shutoff connectors with the proper, straight through type of connector.

Straight Through Connectors
These connectors consist of a socket with a sliding locking ring and a plug. The locking ring is held in locked position when it is released. A snap ring set in a groove on the outside of the connector body keeps the spring from pushing the locking ring off of the body.

When the ring is pulled back to the open position, the balls set in holes in the socket body are free to slide out, releasing the plug. When the ring is in the locked position, the balls are pressed and held to the inside of the socket and the plug is locked firmly in the socket. The plug is machined with a groove where the balls are seated when the ring is in the locked position.

Potential Quick Connector Problems
Although quick connects can increase system versatility and ease of operation, they may also provide weak points in that critical part of the system that is being handled by the operator. In some cases a lance attached to a gun with quick connects may wobble after a short period of use.

Leaking can occur at quick connects due to o-ring deterioration or damage. A bad connection can present a potential safety problem when the connection fails under high pressure or with extremely hot water.

Sticking, Wear And Expansion
Sometimes it may be hard to remove the plug from a quick connect socket when the ring is pulled back, if so, try twisting or rotating and pulling the plug at the same time. In most cases this will remove the plug. Once the plug is removed, inspect the plug groove for wear caused by the balls pressing into the side of the groove. Such wear is most common with brass plugs. The ball wear pattern consists of small circular indentations.

If this wear pattern is apparent, the end of the plug may have expanded to the point where the fit is too tight for the plug to be easily pulled from the socket. This can be corrected by filing the plug where the locking balls have made a depression so deep and so wide that there is a definite lip. Simply file off or otherwise remove this lip for easier separation.

If there is no ball wear pattern or apparent distortion, lubricate the inside of the socket with Vaseline, pressing the lubricant in around the balls before the socket is reinserted. Lubrication will ease operation of the connector.