Gnomon: Investigating Plumbing
Created | Updated Apr 3, 2018
Ireland has various types of plumbing and fittings:
Copper pipe
Pex - a plastic pipe suitable for hot or cold water. Qualpex is a common make.
Compression joints
Push together joints
Solder joints - very rare
Irish pipe is made in Imperial sizes:
"Half-inch" has an internal diameter of a half inch, and an external diameter of 14.7mm. This makes it virtually indistinguishable from English standard pipe, which is 15mm.
"Three-quarter-inch" is also very similar to but not the same as the English standard 22mm.
Compression Joints
These are used for things like joining two pipes together in a straight line, joining two pipes together at 90 degrees, joining three pipes in a T formation, adding a tap on the end of a pipe, adding an inline stopcock, or a "cap" to close a pipe at the end because it is not needed.
Compression joints are usually made of brass. They have three parts - a solid brass bit, a ring with screw threads known as a nut, and a small ring known as an olive.
When attaching a copper pipe to a compression joint, put the nut on the pipe, then thread the olive onto the pipe. The pipe is slid as far as it can go into the pipe-shaped hole in the joint, the olive is slid up the pipe until it is snug against the joint, then the nut is screwed onto the compression joint to lock the pipe in place. The first time you tighten the nut, huge force is needed. This compresses the olive and bends it so that it cuts into the pipe and clamps itself onto it permanently. The olive makes a watertight seal with the rest of the joint. You can then unscrew the nut to open the joint and tighten it to close it again without too much force.
If using plastic "pex", there is one extra step - you need to insert a special copper cylinder into the end of the pex pipe, so that when you tighten the nut the pipe doesn't just collapse.
English and Irish standards in compression joints
The nuts used for the two standards are virtually identical. English ones have 15mm written on them and Irish ones have 1/2" but they be can used interchangeably. For neatness you should use the nut to match the standard but at a pinch you can mix them.
The difference between English 15mm and Irish 14.7mm pipe is so small that it is very hard to tell them apart by eye or even by measuring them. An English olive will fit snugly on an English pipe and will be slightly loose on an Irish pipe. An Irish olive will fit snugly on an Irish pipe and will not go onto an English pipe. This is how you can tell them apart.
You should always use the right olive for the size of the pipe. Do not use an English olive with an Irish pipe, even though it can be placed on the pipe.
English pipes will not fit into Irish compression joints. Irish pipes will fit into English compression joints and work reasonably well as long as you use Irish olives on them.
Push-Together joints
I haven't used these and don't know much about them. They seem to come in two types - brass and plastic. I assume that the brass ones are suitable for either copper or plastic pipe while the plastic joints are only suitable for plastic pipe.
If using plastic pipe with a push-together joints, you should put a plastic cylinder insert into the pex pipe end before pushing it into the joint.
I don't know if there is any way to take apart a push-together joint once its been used.
Bending a Pipe
There are three ways to bend a pipe:
- add a 90degree elbow joint
- if it is copper, insert a bending spring into the pipe which supports the inside of the pipe, then carefully bend it around your knee. Remove the bending spring.
- if it is pex, it bends easily by hand
Copper pipe
Pex - a plastic pipe suitable for hot or cold water. Qualpex is a common make.
Compression joints
Push together joints
Solder joints - very rare
Irish pipe is made in Imperial sizes:
"Half-inch" has an internal diameter of a half inch, and an external diameter of 14.7mm. This makes it virtually indistinguishable from English standard pipe, which is 15mm.
"Three-quarter-inch" is also very similar to but not the same as the English standard 22mm.
Compression Joints
These are used for things like joining two pipes together in a straight line, joining two pipes together at 90 degrees, joining three pipes in a T formation, adding a tap on the end of a pipe, adding an inline stopcock, or a "cap" to close a pipe at the end because it is not needed.
Compression joints are usually made of brass. They have three parts - a solid brass bit, a ring with screw threads known as a nut, and a small ring known as an olive.
When attaching a copper pipe to a compression joint, put the nut on the pipe, then thread the olive onto the pipe. The pipe is slid as far as it can go into the pipe-shaped hole in the joint, the olive is slid up the pipe until it is snug against the joint, then the nut is screwed onto the compression joint to lock the pipe in place. The first time you tighten the nut, huge force is needed. This compresses the olive and bends it so that it cuts into the pipe and clamps itself onto it permanently. The olive makes a watertight seal with the rest of the joint. You can then unscrew the nut to open the joint and tighten it to close it again without too much force.
If using plastic "pex", there is one extra step - you need to insert a special copper cylinder into the end of the pex pipe, so that when you tighten the nut the pipe doesn't just collapse.
English and Irish standards in compression joints
The nuts used for the two standards are virtually identical. English ones have 15mm written on them and Irish ones have 1/2" but they be can used interchangeably. For neatness you should use the nut to match the standard but at a pinch you can mix them.
The difference between English 15mm and Irish 14.7mm pipe is so small that it is very hard to tell them apart by eye or even by measuring them. An English olive will fit snugly on an English pipe and will be slightly loose on an Irish pipe. An Irish olive will fit snugly on an Irish pipe and will not go onto an English pipe. This is how you can tell them apart.
You should always use the right olive for the size of the pipe. Do not use an English olive with an Irish pipe, even though it can be placed on the pipe.
English pipes will not fit into Irish compression joints. Irish pipes will fit into English compression joints and work reasonably well as long as you use Irish olives on them.
Push-Together joints
I haven't used these and don't know much about them. They seem to come in two types - brass and plastic. I assume that the brass ones are suitable for either copper or plastic pipe while the plastic joints are only suitable for plastic pipe.
If using plastic pipe with a push-together joints, you should put a plastic cylinder insert into the pex pipe end before pushing it into the joint.
I don't know if there is any way to take apart a push-together joint once its been used.
Bending a Pipe
There are three ways to bend a pipe:
- add a 90degree elbow joint
- if it is copper, insert a bending spring into the pipe which supports the inside of the pipe, then carefully bend it around your knee. Remove the bending spring.
- if it is pex, it bends easily by hand
