Multikwik News

01 February 2009 / Don't Get Trapped!

Trap

The humble waste trap. How can one of the seemingly simplest items cause so many headaches. To avoid costly call-backs, Steve Hopkins from Hunter Plastics, answers some of the most commonly asked questions about these essential items.

Q1: How can I comply with the building regs when fitting a trap underneath a shower or bath?

A: Modern shower trays can leave only a pitifully small gap underneath to fit an effective waste trap.

In 1994 BS 5572, the standard which required a 76mm deep water seal for baths and showers, was revised downwards to 50mm. BS5572 was superseded by BSEN12056:2000 in 2000 but 90% of the requirements remain, including the 50mm seal.

A 50mm water seal gives installers a fighting chance to fit a trap that meets the Standard! Although it is possible to fit a running trap away from the shower tray, this can be awkward because it requires extra fittings to complete the job and it still needs to be hidden from sight afterwards.

The best solution is to fit a shower tray trap specially designed for the job like the compact shower trap from Multikwik. The trap has an elongated water body, which achieves a 50mm seal in a trap that is just 90mm (3½") deep.

Q2: In the past I've been called back to installations because of leaky traps. What should I look for when I buy a trap?

A: This is the classic problem that most installers face. But there are some things you can look for that can minimise the chances of expensive call-backs:

1. Nuts on traps should be tightened properly. Look for products that can be easily hand tightened especially when hands are wet and reaching into hard-to-get-at places.

2. Smooth, clean, internal surfaces will facilitate self-cleaning and avoid debris build-up.

3. A slip ring that will help nuts to turn, even when they are in firm contact with the seal.

4. Ensure that the compression nut, slip ring and rubber seal are on the waste pipe in the correct order.

5. Look after the traps! Make sure that the trap you buy can stand up to a bit of wear and tear. This can be as simple as the trap being well packaged.

Do not to over-tighten the nuts as it can damage the seal. Over tightening usually happens when you use a wrench - Multikwik traps have been designed so that all you need to do is firmly hand tighten.

Q3: One problem with traps is siphonage where foul air enters the room or there's an annoying gurgling sounds when an appliance is discharged. What can I do to avoid siphonage?

A: Siphonage occurs when negative pressure draws air into the waste pipe as the waste water from a bath or basin discharges and pulls the water seal from the trap with it.

There are three types of siphonage:

1. Self-siphonage: when discharge from an appliance causes loss of seal in its own trap

2. Induced siphonage: when the seal is lost in a trap because of the discharge of another appliance connected to the same waste pipe

3. Compression siphonage: when a falling body of water in a vertical pipe compresses the air below it and forces the water seal from lower appliances' traps

In circumstances where siphonage is occurring regularly because of the pipework arrangement, but it is not possible to install secondary ventilation, use a resealing trap. By drawing air in through the waste outlet before the water seal is dispersed, a resealing trap counteracts siphonage before it can threaten the integrity of the seal.

But resealing traps can be noisy and do not completely eliminate water seal loss. Multikwik has come up with a special anti-siphon unit to allow air to enter the waste system as pressure drops while waste water discharges. It is ideal for commercial complexes with many in-line basins or on any installation with long pipe runs, as well as vertical waste pipes on basins.

Q4: What is a utility trap and what are the benefits?

A: Utility traps take the waste not just from a sink, but also from a washing machine and dishwasher.

There is no reason why one trap (a double bowl kit) can't take wastewater from two adjacent or combined sinks; if they have the correct nozzle configuration, from a dishwasher and washing machine as well. The benefits to the installer are obvious - less cost, less time, less pipework and less hassle.

Q5: Help! I'm completely stuck! What should I do?

A: Don't panic! Help is at hand! All of the reputable manufacturers of traps have technical departments to get you out of that really tight spot. You can reach ours on 020 8855 9851.