Guide to Double Containment Pipework

Systems Available

 DUOSAFE Flex

 

There are Two hose types available in the flexible system; Aquachem & Hydrachem.

Each hose looks the same in appearance, but will be marked along its length with the type of hose that it is.

Aquachem is a Black TPU (PVCU Plasticised) liner, surrounded by nylon braiding for strength, covered by a white PU coating for aesthetic reasons.

Hydrachem is also a Black liner but is a LOPE material surrounded by a Natural PE Liner, some Braiding and the White PU Coating for aesthetic reasons.

IPS Flow Systems hold the latter Hydrachem in stock, for no other reason that it generally covers all the chemicals that need transporting.

The hose does carry a warranty with it and is WRAS approved. However only the designed fittings for the system should be used, as it has been known for standard hose tails to cut through the liner, causing the media to get behind the liner and De-Laminate the lining. If this happens, and standard fittings have been used, then the warranty will be null and void.

 

 

This System is generally a "A" to "B" system, and has only three fittings available in its range. These are the termination fittings for the hose and are made from PVCU only. They are special fittings designed to fit the hose bore with no sharp edges, and utilise a special Stainless-Steel clip to keep the hose in place. The fittings are designed in such a way that when pressure builds inside the hose and forces the fitting to push from the end of the hose, the hose gets tighter on the fitting, as the fitting is tapered. If you look at the page entitled PHR**ADOS, you will see a cross section of the fitting itself; where it shows the letter "A", that is where the retaining band should be placed.

These bands need to be applied with a special pair of piers.

The hose does have a bend radius applied to it, which is 8 x the Outside Diameter of the Outer Hose. If this can't be accommodated, then special contained, splash proof only boxes can be produced with an elbow inside, or indeed other fittings like tees, valves etc, however these can sometimes be as big as the standard radius of bending the hose, or the space intended.

The inner hose is rated at 10 bar with water at 20 Deg C, but the outer is purely for containing the media in a leak situation, and is not pressure rated.

 

Fittings

As previously stated, there are three types of fitting (please see drawings further down this sheet).

PHR**ADOS - This fitting fifs the inner hose only. It leaves the outer hose open to be connected to a bund, or cabinet, and allows either a spigot connection or Female threaded connection to the inner hose

PHR**AOT - This connects to the outer only, allowing the inner hose to pass through completely. The fitting has a spigot connection to connect to fittings in a bund or cabinet.

PHR**ADUAL - This fitting connects to inner and outer hose, sealing the outer and leaving a Female thread on the inner. Please note that it is not advisable to use 2 x DUAL fittings either end of the hose, in a pressurised pumped system. If a leak occurs then the annular space can fill and become pressurised, and in certain situations can balloon and burst. If this happens then chemicals can spray into the surrounding area.

 

Zone fittings are not available in a true fitting, but fitting a "Catch Pot" gives the same effect. Basically, a Grey PVCU box with clear lid, gasket and Stainless-Steel bolting can be used as a leak detect box. The outer hose is cut and connected to the outside of the box, and the inner hose cut and connected inside the box. If a leak occurs then it finds its way to the box for visual leak detection, or by mechanical or electrical detection (not supplied by IPS). These boxes can be utilised with valves, actuated valves, check valves and fittings, but are only splash proof and are not pressure rated.

If used as a true leak detection, these boxes must be placed at the lowest point in the system. If used in conjunction as a zone fitting, then only the length of hose leaking need be replaced in the event of a leak, saving money for the client.

If a Leak detect fitting is required, but a box is too big, then it is possible to utilise a tee with various fittings off the branch, but these can only be fit at the start or end of the hose installation.