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FAQs: drainage products

+ How can I get the correct fall when laying a pipe?

Getting the right gradient – or fall – when pipe laying used to be a tricky thing but no longer. The Metex Pipefall gradient measuring tool makes it easy to get the right fall.

Pipefall is pre-set to measure the following gradients 1:40 1:60 1:80 1:00. You simply set the required fall ratio, place Pipefall on top of the pipe and like a normal spirit level the air bubble will tell you when you have the required gradient. It’s as simple as that.

+ What is the Correct Fall for an Underground sewerage pipe?

The minimum / maximum fall – gradients – are defined in Part H of Building Regs. Between 1:10 to 1:80 fall is prescribed for 100mm pipe but of course it depends what flow rate you wish to achieve. To quickly and easily get an accurate fall measurement use Pipefall from Metex.

+ What is meant by “fall” in plumbing and drainage terms?

Fall is the difference in level between two fixed points. In plumbing work the fall is always in the direction of the flow. It is typically expressed as a ratio such as 1:20 1:40 1:80 or a percentage 5% 2.5% 1.25% or (n.b. there was some rounding of these percentages).

+ How do I calculate pipe gradient or fall?

Well – you can either calculate it manually – like this…

If your final drain length is 15 feet and you are going to slope the line at the minimum 1/4-inch per foot, the drain has to slope a total of 3 3/4 inches from the start of the pipe to the end. To determine the slope, multiply the slope by the length of the line, in this case, 1/4 by 15. But if your drain route requires a bend or turn, you have to calculate the slope of each piece of pipe separately. If you have to route a longer drain pipe without a lot of space, you may opt for a deeper slope up to the maximum of three inches per foot. For example, if you want to route that same 15-foot drain pipe at a slope of three inches per foot, the drain has to slope a total of 45 inches from start to finish. To determine the total slope, you will multiply three by 15.

OR – you can use Pipefall from Metex. Just like using a standard spirit level – no painful mental arithmetic calculations – just set the fall level you want and lay Pipefall on the pipe. Save time and get it right.

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