Installing equipment
Pumps, tanks and water heaters are heavy. Install them on a flat concrete base, fixed with anchor bolts. Rubber or spring pads stop vibration from travelling into the building. Leave space around the machine for repair, and join it to the pipes with flexible connectors so the pipes are not stressed.
Check the position with a spirit level. Line up the pump shaft and motor shaft so that they do not rub.
Piping work
1. Supports. Fix supports at regular gaps so the pipe does not sag. Thin pipes need closer supports than thick ones (for example about 1 to 2 m for small steel pipe). Add a support near every change of direction and valve.
2. Slope. Drain pipes work by gravity, so they must fall. A common slope is 1 in 50 (2%) for small drains: drop = length × slope. A 10 m pipe at 2% drops 0.2 m.
3. Joints. Joints can be threaded, welded, glued (plastic), soldered (copper) or flanged (two rings with a gasket and bolts). Tighten flange bolts in a cross pattern, a little at a time.
4. Other care. Cut pipes square and remove burrs. Slide pipes through walls in sleeves. Label the pipes by colour (for example red for fire water). Fit valves where the plan shows them.
Testing
- Pressure (hydrostatic) test for water and fire pipes: fill with water, remove air, raise the pressure to about 1.5 times the working pressure and hold it (for example 2 hours). The gauge must not fall.
- Water-fill or smoke test for drains: fill the drain with water or smoke and look for leaks or bad smells.
- Function test: run the pump, open a test valve on the sprinkler, ring the alarm.
Never test with air at high pressure; air stores energy and a failure is dangerous. Use water.
Inspection and maintenance
Equipment must be looked after on a plan. Keep a log book.
- Weekly or monthly: look at gauges, valves open, tank level, alarm panel.
- Every year: test fire pumps, check sprinkler heads for paint or damage, clean strainers.
- Sanitary: clean traps and drains, check septic tank or sump levels, repair dripping taps early.
Fix every fault at once and record it.
Try it: the soap-bubble check
On a safe tap or a bicycle tube joint, put soap water on the joint. Guess first: will it bubble? Bubbles show a leak. Plumbers use this idea with water pressure and a gauge.
Key formulas and definitions
- Drain drop (m) = length (m) × slope; 1 in 50 = 2% = 0.02
- Test pressure ≈ 1.5 × working pressure
- Leak % = (start pressure - end pressure) ÷ start pressure × 100
- Four S: Stand firm, Support, Slope, Seal & test
Worked examples
1. A drain is 10 m long with slope 1 in 50. How much does it fall?
10 × 0.02 = 0.2 m (20 cm).
2. Working pressure is 8 bar. Find the test pressure.
1.5 × 8 = 12 bar.
3. A 12 m pipe needs supports every 2 m. How many supports?
Gaps of 2 m along 12 m: supports at 0, 2, 4, 6, 8, 10, 12 m = 7 supports (6 if the ends are fixed by the equipment).
4. During a test the gauge falls from 15 bar to 14.4 bar. What percent is lost?
(15 - 14.4) ÷ 15 × 100 = 4%. This is a leak; find the joint.
5. Why do we use a flexible connector between a pump and a pipe?
The pump vibrates. A flexible connector stops the vibration moving into the pipe and relieves stress.
6. A 25 m drain must drop 0.5 m. What slope is that?
0.5 ÷ 25 = 0.02 = 2%, or 1 in 50.
Common mistakes
- Laying a drain flat. It will not drain.
- Tightening one flange bolt fully before the others. Tighten in a cross pattern.
- Testing with high-pressure air instead of water.
- Skipping supports. The pipe sags and joints leak.