Difference between revisions of "Waste pipe"
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Uses of the sizes: | Uses of the sizes: | ||
* 21.5mm - overflow pipe from cisterns, not used for sink waste | * 21.5mm - overflow pipe from cisterns, not used for sink waste | ||
| − | * 32mm - for | + | * 32mm - for a basin |
| − | * 40mm - for washing machine, can service several appliances | + | * 40mm - for kitchen sink, washing machine etc, can service several appliances |
* 50mm - for more than 4 appliances | * 50mm - for more than 4 appliances | ||
Larger sizes also exist, and are used in flats and large houses. | Larger sizes also exist, and are used in flats and large houses. | ||
| − | |||
| − | |||
There are 2 types of pipe, solvent weldable and non-weld. For a given nominal size, | There are 2 types of pipe, solvent weldable and non-weld. For a given nominal size, | ||
| Line 27: | Line 25: | ||
* Non-weld pipe is for pushfit fittings | * Non-weld pipe is for pushfit fittings | ||
* Compression fittings usually fit both types of pipe | * Compression fittings usually fit both types of pipe | ||
| + | |||
| + | If fittings are stiff, a little grease can help - but not on solv weld of course. | ||
| Line 32: | Line 32: | ||
Least tendency to deposit solids occurs with a fall of -. New pipework should have a fall of - to - to comply with building regs. | Least tendency to deposit solids occurs with a fall of -. New pipework should have a fall of - to - to comply with building regs. | ||
| − | Occasionally waste pipework is seen that flows '''uphill'''. Water isn't so keen on going upwards, and such arrangements tend to either not work or collect solids and be prone to blocking. | + | Occasionally waste pipework is seen that flows '''uphill'''. [[Water]] isn't so keen on going upwards, and such arrangements tend to either not work or collect solids and be prone to blocking. |
| Line 38: | Line 38: | ||
Solvent weld | Solvent weld | ||
* small & slim | * small & slim | ||
| − | * cheap fittings | + | * relatively cheap fittings |
| − | * use solv weld pipe only, the other type | + | * use solv weld pipe only, the other type won't fit or weld |
* undoing a solvent weld is completely impossible, the plastic fuses together becoming one piece | * undoing a solvent weld is completely impossible, the plastic fuses together becoming one piece | ||
| − | * To fit, wipe the fitting and pipe clean, brush on pipe weld solvent, assemble the joint and let it set. If the pipe isn't clean, use a scourer first | + | * To fit, wipe the fitting and pipe clean, brush on pipe weld solvent, assemble the joint and let it set. If the pipe isn't clean, use a [[Scraper|scourer]] first |
| − | * Solv weld piping | + | * Solv weld piping sometimes lacks access points, as no joints can be undone. Where access is needed, an access point can be included (or even a compression or pushfit tee, if preferred). |
Compression | Compression | ||
* bulkier | * bulkier | ||
* more money | * more money | ||
| − | * | + | * generally these fit all variations of a given nominal size of pipe |
* undoable | * undoable | ||
| − | * reusable if the rubber rings are ok | + | * reusable if the rubber rings are ok (replacements are available) |
| − | * check its watertight after fitting, as its possible for the rubber ring to sit wrong and allow leakage | + | * check its watertight after fitting, as its possible for the rubber sealing ring to sit wrong and allow leakage |
Pushfit | Pushfit | ||
| Line 56: | Line 56: | ||
* Some are easy to remove | * Some are easy to remove | ||
* Generally won't fit solv weld pipe | * Generally won't fit solv weld pipe | ||
| − | * Joints | + | * Joints can be pulled apart, so proper pipe support is necessary. |
==Compliance== | ==Compliance== | ||
| − | New pipework must be building regs compliant at time of fitting. Old pipework need not legally meet any building regulations, current or past, and upgrades of such pipework are at the discretion of the householder. A lot of non-compliant pipework works | + | New pipework must be building regs compliant at time of fitting. Old pipework need not legally meet any building regulations, current or past, and upgrades of such pipework are at the discretion of the householder. A lot of non-compliant pipework works fine in practice. |
| Line 66: | Line 66: | ||
* Correct fall | * Correct fall | ||
* Straight as possible runs, minimise the of use right angle joints | * Straight as possible runs, minimise the of use right angle joints | ||
| − | * Enough access points to enable rodding the full length of the pipe. | + | * Enough access points to enable [[Unblock a Drain|rodding]] the full length of the pipe. |
* Where space permits, a swept bend is better than a sharp right angle | * Where space permits, a swept bend is better than a sharp right angle | ||
* Avoid putting any cooking fat or solids down the sink. Molten fat causes lots of blockages. | * Avoid putting any cooking fat or solids down the sink. Molten fat causes lots of blockages. | ||
| Line 85: | Line 85: | ||
The main ways to cut plastic waste pipe are: | The main ways to cut plastic waste pipe are: | ||
* Plastic pipe cutters - these look like giant secateurs | * Plastic pipe cutters - these look like giant secateurs | ||
| − | * Saw - most types will do it. | + | * [[Saw]] - most types will do it. |
| − | Sawn ends need the outer burr trimming off with a knife. | + | Sawn ends need the outer & inner burr trimming off with a [[Knives|knife]]. |
==Clips== | ==Clips== | ||
| − | Plastic pipes sag under the load of water easily, and should be clipped to the wall. Failure to do so results in sag, | + | Plastic pipes sag under the load of [[water]] easily, and should be clipped to the wall. Failure to do so results in sag, increased risk of blockage and tendency for the pipe to pull out of pushfit or compression fittings. |
| + | |||
| + | Different types and brands of pipe clips have differing pipe to wall spacing. | ||
| − | + | If you're missing a clip somewhere and the pipework will be out of sight, a [[screw]] into the wall can be used to support it. | |
Revision as of 01:12, 30 November 2010
Pipe Sizes & Types
The (nominal) sizes of waste pipe used for domestic houses are
- 21.5mm
- 32mm (aka 1.25")
- 40mm (aka 1.5")
- 50mm (aka 2")
Uses of the sizes:
- 21.5mm - overflow pipe from cisterns, not used for sink waste
- 32mm - for a basin
- 40mm - for kitchen sink, washing machine etc, can service several appliances
- 50mm - for more than 4 appliances
Larger sizes also exist, and are used in flats and large houses.
There are 2 types of pipe, solvent weldable and non-weld. For a given nominal size,
- solv weld pipes are all the same real size.
- non-weld pipes are fractionally bigger
- exact non-weld pipe size varies a bit between manufacturers
- Just to be helpful, all these variations are described using exactly the same nominal size description.
- Solv weld pipe is for solv weld fittings
- Non-weld pipe is for pushfit fittings
- Compression fittings usually fit both types of pipe
If fittings are stiff, a little grease can help - but not on solv weld of course.
Fall
Least tendency to deposit solids occurs with a fall of -. New pipework should have a fall of - to - to comply with building regs.
Occasionally waste pipework is seen that flows uphill. Water isn't so keen on going upwards, and such arrangements tend to either not work or collect solids and be prone to blocking.
Types of fitting
Solvent weld
- small & slim
- relatively cheap fittings
- use solv weld pipe only, the other type won't fit or weld
- undoing a solvent weld is completely impossible, the plastic fuses together becoming one piece
- To fit, wipe the fitting and pipe clean, brush on pipe weld solvent, assemble the joint and let it set. If the pipe isn't clean, use a scourer first
- Solv weld piping sometimes lacks access points, as no joints can be undone. Where access is needed, an access point can be included (or even a compression or pushfit tee, if preferred).
Compression
- bulkier
- more money
- generally these fit all variations of a given nominal size of pipe
- undoable
- reusable if the rubber rings are ok (replacements are available)
- check its watertight after fitting, as its possible for the rubber sealing ring to sit wrong and allow leakage
Pushfit
- Quick & easy to use
- Some are easy to remove
- Generally won't fit solv weld pipe
- Joints can be pulled apart, so proper pipe support is necessary.
Compliance
New pipework must be building regs compliant at time of fitting. Old pipework need not legally meet any building regulations, current or past, and upgrades of such pipework are at the discretion of the householder. A lot of non-compliant pipework works fine in practice.
Blockage prevention
- Correct fall
- Straight as possible runs, minimise the of use right angle joints
- Enough access points to enable rodding the full length of the pipe.
- Where space permits, a swept bend is better than a sharp right angle
- Avoid putting any cooking fat or solids down the sink. Molten fat causes lots of blockages.
Badly designed pipework with very poor flow is occasionally seen. With this, an occasional flush can help reduce solids build up, lessening the risk of blockage. This is easily done by eg filling the sink at the beginning of the pipe run to the brim, and letting it flush the pipe.
Impending blockages are easier to clear than a blocked pipe, and can be spotted in 3 ways:
- sink drains very slowly
- outflow of pipework very slow (visible on old open drain systems)
- Trickling sound of pipework continues awhile after the sink etc is empty
Unblocking
Cutting
The main ways to cut plastic waste pipe are:
- Plastic pipe cutters - these look like giant secateurs
- Saw - most types will do it.
Sawn ends need the outer & inner burr trimming off with a knife.
Clips
Plastic pipes sag under the load of water easily, and should be clipped to the wall. Failure to do so results in sag, increased risk of blockage and tendency for the pipe to pull out of pushfit or compression fittings.
Different types and brands of pipe clips have differing pipe to wall spacing.
If you're missing a clip somewhere and the pipework will be out of sight, a screw into the wall can be used to support it.