Drip Tube Keeps Coming Apart

Q:  The pressure is blowing off the pipes/tubes from the barbed fittings on my drip irrigation system.  This is only happening on hot days (30°C=86°F in the shade).  Pipe temperature could be as high as 45°C=113°F.  Our water pressure varies between 2.5 and 3.1 bar (35 and 45 PSI.)

A:  Drip tube should not blow off the barbs, even on a hot day when the temperature softens the plastic tubing (however the heat does make it easier for them to blow off!)  There are three common reasons the tubes blow off.

1. The most common problem is that the water pressure is too high.  This is probably your problem.  The water pressure should be around 1.3 to 2.0 bars (20 – 30 PSI).   You should install a pressure reducer after your valve to lower the pressure.

2.  The pipe and fittings may not be the same size.  This is one of the pitfalls I warn about in my Drip Guidelines.   16mm and 18mm tube  are both commonly referred to as 1/2 inch in the USA! The fittings for these two are not interchangeable.

3. Pressure spikes can pass through the less expensive pressure reducers often sold for drip systems.  If you have high water pressure this may be the problem.  The solution is to install a high quality brass pressure reducer valves.  These generally are sold in the plumbing department rather than the irrigation department of stores and cost $50.00 or more.

Common sizes are 12 mm (0.455″ or 3/8″), 16mm (0.620″ or 1/2″), 18mm (0.720″ or 1/2″), and 24mm (0.940″ or 3/4″). Do you see the problem? Two sizes are commonly referred to as “1/2 inch” in the USA! The fittings for these two are not interchangeable.