To change a valve, replace defective components or expand work, the water does not always have to be drained off. Here is the use of Freezers makes sense.
Pipe frosting can with all media that freezable portions included. Freezing work on pipelines is carried out by special companies with the appropriate equipment in the dimensions DN 50 to DN 300 (pipe freezing, pipe freezing).
Because water in pipes can only freeze if no current is available, the pump must be switched off, radiator valves closed or water withdrawal prevented before freezing. In addition, the pipe contents should be cooled to room temperature before freezing.
Another important consideration for pipeline freezing is when the Heating system properly prepared or treated was, so the system was filled or treated with appropriate water. In this case, as little water as possible should be emptied so that the quality of the water continues to be correct. To a Water analysis But you won't get around in spite of this.
If there is no asset book, a water analysis may also be necessary before start the freezing work is done because some system is also using Antifreeze can be filled. The appropriate freezing system must then be selected here.
|Requirements for freezing work (pipe freezing): |
- The medium to be frozen must contain parts that can be frozen (e.g. water)
- There must be no current in the pipeline in the area of the pipe frost
- The pipe must be completely filled with the medium to be frozen (e.g. water)
- The material of the pipeline must be suitable for the freezing process
- Maximum operating temperature of the medium to be frozen 50 degrees Celsius
- Maximum operating pressure 40 bar
- There must be enough space to mount the freezing collar
- There must be no weld seam in the immediate area of the pipe freezing
- The nitrogen tank should be placed in the immediate vicinity of the freezing work
|Areas of application of the freezing process "Pipe freezing":|
- Integration of system parts, gate valves or valves
- Replacement of fittings, valves or components
- Replacement of defective seals
- Welding work
- Assembly, maintenance or repair work
|Advantages of pipe freezing of pipelines:|
- Costs and time are saved by using the "pipe freezing" process
- Complex emptying of pipelines is avoided
- Follow-up work is no longer necessary (e.g. venting)
- Contaminated water does not have to be disposed of
Source: TAS swing hammer
Pipe freezing - pipeline DN 100
Operating pressure: 6 bar, approx. 15 ° C
Reason for the pipe freezing: replace the defective slide
Source: TAS swing hammer
|Electric freezer (chiller) |
The Plug-in pipe freezing device (220 volts) works with a hermetically sealed refrigerant circuit. This allows copper pipes with an outer diameter of 10 to 42 mm and steel pipes of 1/4 "to 1 1/4" to be frozen. Since this method of freezing does not generate any refrigerant vapors, it can be used anywhere, including in shafts and in rooms that are below ground level.
- Refrigeration unit
- Freezing heads (cooling tongs)
- Refrigerant hoses
- LCD digital thermometer
|Way of working|
There is a cooling machine (heat pump) in the freezer. The compressor sucks in the refrigerant vapor from the two cooling tongs and compresses it to the condenser pressure, causing a considerable increase in temperature. In the condenser (liquefier), the refrigerant vapor gives off heat to the environment and thus becomes liquid. If necessary, a fan is switched on to support the cooling process and the cooling of the compressor. The liquid refrigerant flows through a throttle device through the two hoses to the cooling tongs and relaxes. The refrigerant evaporates, reaching a temperature of -30 ° C, drawing heat from the pipe points under the tongs and thus from the water. This cycle continues until there is no more heat in the pipes.
Insulating sleeves are placed around the cooling tongs so that drafts (heat supply) do not hinder the freezing process and the pipe can be blocked for hours or days by means of ice plugs. The pipe temperature is indicated by a digital thermometer via thermal sensors in the cooling tongs.
|Carbonated pipe freezer |
This relatively simple method only requires a carbonic acid bottle (carbon dioxide - CO2) with appropriate hoses and freezing collars. The ice plugs that form withstand a pressure of up to 500 bar.
Since the density of carbon dioxide is about 1.5 times that of air, it collects. in shafts delimited on all sides and in rooms whose floors are below ground level and displaces the air in the process. There is a risk of suffocation if there is insufficient ventilation. Therefore, this freezing technique may only be used in a well-ventilated environment.
- Refrigerant bottle (carbonic acid)
- Freezing Cuffs
- Grips with injector
- High pressure hoses
In the steel bottle is liquid carbonic acid (CO2) with over 50 bar pressure. When the liquid carbonic acid relaxes to atmospheric pressure, it immediately changes to the solid state at -79 ° C - a white mass is formed, Carbonated snow called.
Since the carbon dioxide must be supplied to the freezing cuffs in liquid form, only bottles with a riser pipe (dip pipe) may be used.
Source: REMS-WERK Christian Föll and Sons GmbH
|Way of working|
The High pressure hoses are connected to the vertical carbon dioxide bottle. Then the grips are placed on the pipes with the freezing collars that match the pipes.
As soon as the cylinder valve is opened, flows liquid carbonic acid to the handles, relaxes in the injectors and forms dry ice with a temperature of -79 ° C in the freezing collars. This cold is transferred to the water in the pipes. This creates the Ice plugs. Frost forms on the sleeves and on the outer walls of the pipe. This is the sign that the pipes are frozen.
For working with a open flame a distance of more than 60 cm from the freezing points must be maintained. The freezing process must be maintained throughout the duration of the work; the supply of carbonic acid adjusts itself automatically.
After completing the work, the cylinder valve must be closed. The freezing device may only be dismantled when the pressure in the hoses has been reduced and the grips and sleeves have defrosted.
Every freezer has a operating manualthat is also detailed safety instructions so that it can be used as intended.
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