FrostProtection

VärmeKabelTeknik Frost protection

from

Frost protection VärmeKabelTeknik 2

Fields of application

A physical fundamental principal states that all transportation of heat goes from warm zones to cold ones.

This means that for example pipes that are surrounded by low temperatures emit heat through the insulation. The size of the heat loss is depending on the diameter of the pipe, the thickness of the insulation, the material and the difference in the temperature between the pipe and the surrounding. If the heat loss is large enough there is a risk that the liquid in the pipes will freeze or be damaged in some way.

If ice is formed in the pipes there is a risk that the pipes will freeze to.

To prevent ice formation in the pipes due to too low an ambient temperature an easy and effective method is to apply heating cables on the pipes or inside them.

The purpose is not to heat the pipe but to compensate the heat loss in the insulation.

Examples of applications:

• Water‐ and waste pipes which are not placed in a frostproof depth.

• Drainage pipes • Hot well pipes from refrigerating machines.

• Control tubes.

Tanks and cisterns can also be frost protected by the same method.

How does the frost protection operate?

By applying the heating cables, with a suitable power, along the pipes or inside the pipes in direct contact with the medium, the heat is provided that is needed to compensate the heat loss from the pipes.

How about the energy consumption?

The heating cable has a very high efficiency as the heat is generated directly in the return wire of the cable.

The application of the cable is made in such a way that a good thermal contact is obtained between the cable and the medium that is to be frost protected.

These two factors together with a thermostat that is controlling the cable to be switched on only when there is a risk of freezing, make frost protection applications with heating cables very much energy saving.

Rule of thumb:

10 Watt/m is sufficient power to frost protect:

• A 50mm‐water supply and sewer system pipe applied in the ground.

• A 50mm‐water supply and sewer system pipe insulated with 50mm at ‐25oC.

• A 25mm‐water supply and sewer system pipe insulated with 50mm at ‐35oC.

MORE INFORMATION ABOUT CONTROL CAN BE FOUND IN THE CHAPTER K "CONTROL"


3

The most frequently used cable types are TCPR and BTL-10

Those cable types are the most frequently used when you talk about frost protection of water supply and sewer system pipes. The Velox standard lengths are manufactured out of these types.

If the requirement of frost protection or heating up is more sophisticated we refer to the chapter G "Industrial heating".

The TCPR is a series conductor heating cable with return wire and is delivered with termination end and cold‐lead‐in cable mounted.

The TCPR is used for both interior and exterior applications.

The TCPR can be obtained as standard lengths (20‐100m) or as specially designed lengths.

The BTL‐10 is a self‐limiting heating cable with a non‐linear output, i.e. when the ambient temperature goes down the output increases.

The output of the BTL‐10 is changed from almost 0 W/m at +65oC to about 10 W/m at +5oC.

The BTL‐10 can be cut in the exact required length and is therefore well suited to store as an universal frost protection cable

The BTL‐10 is used for both interior and exterior applications.

The BTL‐10 is sold as a "frost‐kit" with cable, connection kit, termination end and caution labels, all packed in a handy "ready‐to‐carry‐box”.

Standard lengths with data and order.no are presented after the chapter ”Dimensioning frost protection”..


Exterior application

The heating cable is applied against the pipe inside the insulation.

At this type of application it is very important that the heating cable is applied close to the pipe that is to be frost protected in order to get a good heat transfer.

When the cable is attached to the pipe, a method to get a good heat transfer is to put an aluminium tape above the cable and against the pipe along the cable.

It is recommended to use glass fabric tape when the cable is to be attached to the pipe, as this tape is heat resistant and at the same time it is good to the cable.

If the required power per meter pipe is corresponding or if it is somewhat lower than the power per meter heating cable, the cable is applied to the pipe and attached with a glass fabric tape across the pipe with a c/c‐distance of 250‐350mm.

If the required power per meter pipe is larger than the power per meter heating cable you have to do a so called "spiral application".

Example: Required power 15 W/m pipe, heating cable 10 W/m. If 1.5m heating cable is applied on 1m pipe you will get 15W/m pipe.

Interior application

The heating cable is applied inside the pipe in direct contact with the medium.

An easy way to frost protect existing and already insulated pipes and at new applications is to apply heating cables inside the pipes.

The advantage with this method is that the cable will get in a direct contact with the medium that is to be heated, which gives a fast melting and less working expenses, as more difficult conditions are solved with a lower output.

Plastic pipes

A heating cable with a higher output than 12W/m should not be applied in direct contact with a plastic pipe as the cables sheath temperature might damage the pipe.

At a higher required power the heating cable can be applied in sand with a distance of some centimetres in order to produce a heat barrier between the cable and the pipe.


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Insulated pipes above the ground.

Rule of thumb for the required power in normal cases:

• Required power 10W/m pipe:

- if the pipe diameter is max. 50mm - if the insulation is min 50mm mineral wool - the lowest ambient temperature is -30oC

In other cases the required power is calculated as per below:

2 x π x dt x k x S P/m = In (dy ÷ di)

P/m = The required power in W/m.

dt = The difference in temperature in °C

(the lowest permitted temperature of the

medium minus the lowest frequent ambient

temperature).

k = The permeability of the insulation material in

W/m°C (J/m°C x 1.16)

For mineral wool 0.046 W/m°C

S = Safety factor, is put to 1.3‐1.7 depending how

it is exposed to weather and wind.

dy = The interior diameter of the insulation in mm

di = The outer diameter of the pipe in mm.

Tanks above ground

Required power:

The total power required is calculated as per below:

A x k x dt x 1.25 x S Pt = I

Pt = The required power (Total power in W)

A = The heatable sheath surface in m².

k = The heat permeability of the insulation in

W/m°C

(for mineral wool = 0.046)

dt = The difference in temperature in °C

(the lowest permitted temperature of the

medium minus the lowest frequent ambient

temperature)

S = Safety factor, is put to 1.3‐1.7 depending how

it is exposed to weather and wind) I = The thickness of the insulation in meter.

More information about heating and keeping pipes, tanks and cisterns warm can be found in chapter G "Industrial heating"


Insulated pipes applied in the ground

Required power:

Are stated in W/m and is calculated as per below:

Pm = 0.021 x dy x mt

Pm = Required power in W/m.

dy = The outer diameter of the pipe in mm.

mt = The surface temperature depending on the

climate zone and the depth of trench (see

table)

Insulated pipes applied in the surface

Required power:

Are stated in W/m pipe and is calculated as per below:

2 x π x k x mt x 1.2 Pm = ln (dy ÷ di)

Pm = Required power in W/m

k = The heat permeability of the insulation in

W/m°C

For mineral wool = 0.045

mt = The surface temperature depending on the

climate zone and depth of trench (see table)

dy = The outer diameter of the insulation.

di = The interior diameter of the insulation.

Underground pipes

At designing of underground pipes the required power has well as the method of installation is effected by the amount of factors as the depth of the underground piping, construction and insulation.

VÄRMEKABELTEKNIK has a great knowledge and experience of different types of heating cable constructions and would be pleased to assist you with advises and recommendations at designing and installation of this type of heating cable applications.

Naturally VÄRMEKABELTEKNIK also take care of the whole designing if you wish.

Surface temperature (mt).

Installation depth in cm

Klimatzon

1 1

25 17.6 25 17.6 25

50 7.0 50 7.0 50

60 6.5 60 6.5 60

80 5.3 80 5.3 80

100 4.1 100 4.1 100

150 1.2 150 1.2 150

200 ‐ 200 ‐ 200


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Frost protection of pipes with self- l imiting heating cable

Cable: BTL‐10

Application: Interior and exterior applications.

Voltage 230 Volt.

The BTL‐10 is a cable of the self‐limiting type with a temperature/power condition adapted to the frost protection.

The BTL‐10 can be cut, connected and terminated directly on the site.

The BTL‐10 is marked by the metre or alternatively packaged in 25, 50, 100 coils together with a sufficient number of connection cables, end terminations for exterior applications. For interior applications a supplementary kit is available as accessory.

Part.no Article

8986130 Cable BTL‐10

8986139 Connection cable/End termination for exterior applications including caution labels.

8986138 Supplement kit for interior applications.

Part.no Article Part.no Article

8986133 Frost box 25 8986133 Frost box 25




Heating cable element for frost protection of pipings

Frost protection on "Pinn‐Pack"

Application: Exterior application.

Voltage: 230V

VärmeKabelTeknik presents a frost protection cable in lengths adapted for a fixed connection including 1m connection cable.

The BTL‐10 self‐limiting heating cable makes you feel safe. There is no risk of overheating.

The "Pinn‐Pack" is available in lengths from 1 ‐ 18m, larger lengths on request. It is supplied with 1m connection cable.

The Pinnpack‐element are also available for interior application in plastic pipes, min. 25

Part.no Length

(m)

Power

(W)

Part.no Length

(m)

Power

(W)

1101010 1 10 1101070 7 70

1101015 1,5 15 1101080 8 80

1101020 2 20 1101090 9 90

1101025 2,5 25 1101100 10 100

1101030 3 30 1101120 12 120

1101040 4 40 1101140 14 140

1101050 5 50 1101160 16 160

1101060 6 60 1101180 18 180

Installation: Interior application

Voltage: 230 V

The Pinn‐Pack‐elements are also available for exterior application for plastic pipes (se above), min 25mm diameter. It is delivered with an exterior tap R20 which you adapt against the tee‐conduit with a nipple.

Part.no Length

(m)

Power

(W)

Part.no Length

(m)

Power

(W)

11020101 1 10 11020701 7 70

11020151 1,5 15 11020801 8 80

11020201 2 20 11020901 9 90

11020251 2,5 25 11021001 10 100

11020301 3 30 11021201 12 120

11020401 4 40 11021401 14 140

11020501 5 50 11021601 16 160

11020601 6 60 11021801 18 180


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Heating cable elements for frost protection of pipings

Cable: TCPR

Application: Interior application.

Voltage: 230 V

The TCPR is a series conductor cable of the return wire type. It is therefore normally applied with one length along the piping.

The kit contains: Heating cable element 2m cold‐lead‐in cable mounted Conduit R20 Caution label

Cable: TCPR

Application: Exterior application.

Voltage: 230 V

The TCPR is a series conductor cable of the return wire type. It can therefore be performed with an air‐tight end termination and be mounted inside a piping.

The kit contains: Heating cable element with 1m cold‐lead‐in cable mounted Caution label

Part.no Denomination TCPR I

Pipe length (m)

Power (Wtot)

Power(W/m)

8987124 20/ 12.00 20 220 10.08987125 25/ 8.00 25 265 9.78987126 30/ 5.35 30 330 10.08987127 35/ 4.00 35 378 9.98987128 40/ 3.90 40 456 10.48987129 45/ 2.90 45 405 8.38987130 50/ 1.90 50 557 10.28987131 55/ 1.90 55 506 8.58987132 60/ 1.30 60 678 10.48987133 65/ 1.30 65 626 8.88987134 70/ 1.00 70 758 10.48987135 80/ 0.65 80 1017 11.68987136 85/ 0.65 85 957 10.38987137 90/ 0.65 90 904 9.28987138 100/ 0.45 100 1175 10.0

Part.no Denomination TCPR F

Pipe length (m)

Power(Wtot)

Power(W/m)

8987154 20/ 12.00 20 220 10.08987156 25/ 8.00 25 265 9.78987158 30 5.35 30 330 10.08987160 35/ 4.00 35 378 9.98987162 40/ 2.90 40 456 10.48987163 45/ 2.90 45 405 8.38987164 50/ 1.90 50 557 10.28987165 55/ 1.90 55 506 8.58987166 60/ 1.30 60 678 10.48987168 65/ 1.30 65 626 8.88987170 70/ 1.00 70 756 9.98987172 80/ 0.65 80 1017 11.68987174 85/ 0.65 85 957 10.38987175 90/ 0.65 90 904 9.28987176 100/ 0.45 100 1175 10.8


VELOX PREFROST

Velox Prefrost is a complete unit with insulated plastic tube (32mm), angle tee and heating cable mounted to an unit, ready for connection to water‐ and supply mains.

Velox Prefrost is available as standard lengths according to the table. Other lengths could be quoted on request.

Control of frost protection applications

A functional and reliable frost protection with minimal power consumption requires that some form of temperature sensitive control equipment control the heating cables operation.

Depending on the extent and requirements of the application, the control can be done by several different methods.

The function of the control depends on the measuring method and the characteristics of the control equipment.

Supply voltage: 220 V.

Part.no Power Pipings Current

(W) (m) (W/m) (A)

8986171 80 6 10.0 0.3

8986172 140 12 10.0 0.5

8986173 200 20 10.0 1.0

8986174 245 25 9.9 1.2

8986175 300 30 10.0 1.4

8986176 345 35 9.9 1.6

8986177 420 40 10.5 2.0

8986178 510 50 10.2 2.2

Measuring methods

Direct measurement:

The most effective and functional best solution is obtained if the transmitter could be placed direct in the medium which is to be frost protected or to be kept warm.

Indirect measurement:

Of different reasons it most often is difficult to apply a transmitter inside a process vessel. In such cases the transmitter is mounted directly against the outside of the process vessel. This method most often gives a quite acceptable accuracy of measurement if it is a good thermal contact between the medium and the transmitter, i.e. that the process vessel is made of metallic material.

Measurement of the ambient temperature:

At smaller applications, type frost protection of water and sewer systems you often can be satisfied with a placement of the transmitter in the ambient space and control the heating cable so that it is switched on when the ambient temperature is that low that there is a risk of freezing. This method works sufficient but do not give the optimum lowest energy consumption.


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Control equipment

THERMOSTATS: With a thermostat you control the application according to the ON/OFF‐method, that means that the heating cable is either switched on or ‐ off.

Thermostats is obtained in a number of different performances and different functioning possibilities as capillary/resistant sensor, secure or variable operating temperature, variable on/off‐difference, disconnecting/ending/shifting contact operation etc.

VÄRMEKABELTEKNIK have an extensive programme of thermostats which always allows us to quote for the application suitable control equipment.

Control cabinets

VÄRMEKABELTEKNIK has an extensive programme for complete equipped control cabinets for control of applications where more widespread surrounding equipment is required such as earth‐leakage‐circuit breakers, relays, alarm exit, fuses etc. except our standard programme, which comprehend different functioning possibilities, we also construct and manufacture control cabinets according to the customers requirement of functioning.


Telephone: +46‐301‐418 50 – Email: [email protected] – Homepage: www.vkts.se

Industrihuset Södra Hedensbyn 43

S‐430 64 HÄLLINGSJÖ S‐931 91 SKELLEFTEÅ

Sweden Sweden

Fax: +46‐301‐418 70 Fax: +46‐910‐881 33

Documents

FrostProtection