SOLAS Plumbing flashcards
SOLAS Plumbing · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Pressure at depth formula
- Pressure equals density times gravitational acceleration times depth (p = rho g h). Water at 10 m depth produces about 1 bar, which is the basis for static pressure in tall buildings.
- Water hammer cause
- A sudden change in water velocity, usually from fast-closing valves or taps, creates a pressure surge. Mitigation includes slow-closing valves, correctly sized pipe, and surge arrestors.
- Copper tube R250 grade
- Light-grade copper tube with the thinnest wall, used for surface-run domestic pipework. Buried, high-pressure, or concealed work needs medium R220 or heavy R200 tube.
- Galvanic corrosion rule
- When two dissimilar metals meet in the presence of water, the less noble metal corrodes. Copper followed by steel in the flow direction accelerates steel corrosion, so a dielectric union is needed.
- Category 5 backflow protection
- Fluid category 5 is a severe health hazard such as faecal or animal waste. Only an air gap (type AA or AB) provides adequate protection; check valves and reduced-pressure zone valves are not sufficient.
- Trap seal depth
- The water seal in a trap must be 75 mm for a WC pan and between 38 and 75 mm for other appliances. Too shallow allows sewer gas through; too deep risks self-siphonage.
- Stack vent termination height
- A soil and waste vent pipe must rise at least 900 mm above the highest branch and terminate at least 900 mm above any opening window, or 3 m horizontally from it.
- Self-cleansing drain velocity
- A drain should achieve about 0.7 m/s at design flow to carry solids without deposition. Velocities above about 3 m/s scour the pipe wall and shorten its life.
- Legionella growth range
- Legionella bacteria multiply between 20 and 45 degrees C, with fastest growth near 37 degrees C. Above 60 degrees C they are killed within minutes; below 20 degrees C they are dormant.
- Hot water storage temperature
- Calorifiers and cylinders should store water at 60 degrees C or above and distribute at 50 degrees C or above, to keep the stored volume outside the legionella growth range.
- Unvented cylinder safety set
- An unvented cylinder requires a 3 bar pressure reducing valve, a 6 bar expansion relief valve, a 7 bar temperature and pressure relief valve, and a correctly sized expansion vessel.
- Radiator output and delta T
- A radiator rated at delta T 50 (75/65/20 degrees C) delivers about 75% of that output at delta T 30 (55/45/20). Lower flow temperatures need larger emitters.
- Condensing boiler efficiency
- A condensing boiler recovers latent heat only when the return water is below about 55 degrees C, so low return temperatures and weather compensation raise seasonal efficiency.
- Cistern air gap
- The float-operated valve outlet must sit at least 150 mm above the spillover level of the cistern, and the warning pipe must be screened to prevent contamination and insect entry.
- Balanced hot and cold supplies
- Mixer taps and showers need hot and cold supplies at similar pressure, usually from the same source, otherwise the blended temperature drifts as pressure changes.
- Pipe sizing loading units
- Each outlet is assigned loading units, summed and converted to a design flow. Pipe is then sized to keep velocity below about 1.5 m/s cold and 1.0 m/s hot.
- Pressure test duration
- Pipework is tested at 1.5 times design pressure or the manufacturer's figure, held for at least 1 hour for plastic and 30 minutes for metal, with a recorded gauge reading.
- New main chlorination
- New mains and storage are chlorinated to 50 mg/l free chlorine for 1 hour contact time, then flushed until the residual falls within the wholesome water limit.
- Radiator balancing differential
- Radiators are balanced so the temperature drop across each is about 10-11 degrees C, achieved by adjusting the lockshield valve while the system runs at design flow.
- Combi pressure loss diagnosis
- Repeated pressure loss on a combi usually means a failed expansion vessel, a leaking pressure relief valve, or a system leak. Isolate the boiler to separate vessel faults from system leaks.
- Diverter valve fault
- A combi giving heating but no hot water often has a stuck diverter valve, a faulty flow sensor, or a blocked plate heat exchanger. Confirm the flow switch signal before replacing parts.
- Frozen pipe thawing
- Thaw a frozen pipe from the outlet end back towards the supply using warm air or a hot pack. Never use an open flame, and check for splits before restoring pressure.
- Confined space oxygen limit
- Entry into a confined space requires atmospheric testing with oxygen between 19.5% and 23.5% by volume, plus flammable and toxic gas checks, a permit and a rescue plan.
- Hot work fire watch
- Soldering, brazing and grinding need a hot-work permit, removal of combustibles, and a fire watch maintained during the work and for at least 60 minutes afterwards.
- Site reduced low voltage
- Portable tools on construction sites use 110 V centre-tapped-to-earth reduced low voltage, with 30 mA RCD protection and current PAT test records available.
- Bernoulli effect in pipes
- In steady flow, the sum of pressure, velocity and elevation energy is constant. Where velocity rises at a restriction, static pressure falls, which explains pressure loss at fittings.
- Water thermal expansion
- Water expands by about 4% in volume when heated from 10 to 100 degrees C. Sealed systems therefore need an expansion vessel or a relief valve to absorb the increase.
- Trap branch distance to stack
- A branch must connect within 450 mm of the trap outlet, or the trap must be separately ventilated, to prevent induced siphonage when the stack carries a full bore discharge.
- Inspection chamber spacing
- Inspection chambers are required at every change of direction, at junctions, and at intervals no greater than 45 m on a straight run of drain.
- Air admittance valve limits
- An air admittance valve admits air to relieve pressure but does not vent foul air. It must be fitted above the flood level of the highest appliance and remain accessible for maintenance.
- Water softener effect
- Ion exchange softeners replace calcium and magnesium with sodium, reducing scale. Softened water should not be used for drinking or infant formula without a separate hard-water tap.
- Handover documentation
- Handover must include the commissioning checklist, as-installed drawings, O&M manuals, guarantee certificates and user instructions for controls, so the client can operate and maintain the system.