Freezing is an effective way of stopping the flow of water so pipes can altered or maintained. Ross Dickinson, technical product manager at Rothenberger, outlines one of many methods of doing this
Pipe freezing is not magic. It is a simple and efficient way of sealing a water pipe or system while simple repairs or maintenance are carried out.
All freezing systems, from the basic jacket or clamp type to the professional electric system, work on the same principle. The temperature surrounding the water-carrying pipe is reduced, either by using a liquid or gas refrigerant to encase the pipe, or by placing an electrically controlled freezing head on the pipe.
The resulting drop in temperature causes the water in the pipe to freeze, forming a solid ‘ice plug’ that blocks the pipe and prevents the water from flowing, allowing work to be carried out on the pipe.
This article focuses on the freeze-clamp type. The Rofrost Rapid is a relatively new freezing kit which uses patented pipe clamps, adapted from the Kibosh pipe repair tool, to contain Quick Freeze pipe-freezing spray and allow it to evaporate slowly, cooling down the wall of the pipe and freezing the water inside it.
Using the Rofrost Rapid could not be easier.
Step 1: Fill the pipe clamp
Carefully tear two foam sections from the perforated foam sheets provided with the Rofrost Rapid freezing kit, and place them into
the cavities inside the pipe clamp.
Step 2: Fit the clamp
Fit the clamp to the pipe correctly, by engaging the latches and squeezing the clamp shut as illustrated. Clamps must be fitted correctly on vertical and horizontal pipework.
Step 3: Set the nozzle up
Insert the straw into the nozzle of the Quick Freeze, and then into the correct fluid-intake hole of the device. The clamps can be rotated on the pipe to allow better access to the hole.
Step 4: Insert the fluid
Keeping the can in an upright position, spray Quick Freeze slowly and steadily, not in full bursts, into the clamp. If liquid is seen spitting from the vent hole, reduce the flow. Only a fine, mist-like stream of gas should be seen coming out of the vent hole. After a short period, frost should start to appear on the clamps
Step 5: Wait for the pipe to freeze
Allow time for the liquid to evaporate from within the clamp to achieve its maximum freezing effect. A fine ‘breeze’ should be felt coming from the vent hole. If the foam is over-saturated with liquid, freezing is harder to achieve.
Because of factors such as ambient air and water temperature and the use of inhibitors, it is impossible to say exactly how long a pipe will take to freeze. However, as a guide, copper pipe freezing should take three to five minutes on a 15mm pipe and five to seven minutes on a 22mm pipe.
Step 6: Check that the flow has stopped
Once the clamps have been in place for at least the minimum stated times, test to see if the water flow has stopped by opening a tap or valve on the line. If no flow is detected, work on the pipe can start. If flow is detected, continue to add Quick Freeze spray until the ice plug is fully formed.
Your questions answered
How long will the freeze last?
Once the pipe freezer is turned off or removed, it takes from 10 to 30 minutes for an ice plug to melt. Periodically topping up the gas, or keeping gas ﬂowing on a reduced trickle, will ensure the ice plug remains solid and does not melt. With our electric pipe freezers, the same effect is achieved by leaving them permanently switched on.
Can you freeze in any position – on vertical pipes as well as horizontal runs?
Yes. All Rothenberger pipe freezers will freeze in both a vertical and a horizontal position, although wherever possible a horizontal set-up is more effective and efﬁcient.
Can I freeze moving water?
No. All pipe freezers will arrest and freeze moving water if it is a drip or trickle, but it is not safe to state that moving water can be frozen with any standard, off-the-shelf pipe-freezing products. It is possible to freeze running water with liquid nitrogen, but this is a specialised process and only carried out by dedicated cryogenic freezing contractors.
Can I freeze hot water?
Theoretically, yes, but it is naturally more difﬁcult than freezing cold water. Owing to the high probability of convection currents in hot water, we do not recommend that this is attempted.
How will I know when the pipe is frozen?
Visual signs of freezing will be apparent around the freeze head – or jacket – and on the hoses. Water outflow via a tap stops. Often, a crack can be heard as the ice plug meets in the centre of the pipe.
Can I freeze plastic and lead pipes?
Yes, but these will take longer to freeze – typically from 1.25 to three times longer than copper tube, depending on the type of pipe freezer used.
Will the ice plug withstand mains pressure?
Yes. All Rothenberger pipe freezing systems will produce ice plugs to withstand a maximum pressure of 120psi or 8 bar.
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