>> Parallel circuit heating tape is designed to be cut from reel lengths and site terminated to suit pipework. The heating tape consists of a number of short heating zones, each connected across a pair of continuous bus-wire conductors.
Each complete heating zone will give its full rated design output with circuit voltage applied to the bus-wire conductors.
The heating tape has a core comprising two bus-wire conductors contained within an extruded silicone rubber sheath. The sheath is notched on alternate sides at predetermined intervals to expose a short section of bus-wire conductor.
Nickel-chrome resistance wire is wrapped at regular spacing around the core as a continuous conductor, making contact with the bus-wires at the exposed points.
After completion of the heater conductor wrapping, a high temperature soldered joint is made at each contact point ensuring that a number of conductor strands are securely bonded to the bus-wires.
An extruded FEP outer sheath is then placed over the core and heater element to complete the heater tape assembly.
For certain applications a heating tape may have a tinned copper or stainless steel braided outer cover.
|Type||Volts||Watt/m||Heater zone length (m)||Max circuit length (m)||Max recomm. pipe temp ºC|
|Conductors||Copper stranded flexible 30/0,25mm (1,5mm²)|
|Heater element||Nickel-chrome 80-20|
|Solder||High melting point 296°C|
|Heater zone||0,5 or 1m according to design output|
|Braid||Stainless steel / Tinned copper|
|Temperature range||Min. -60°C to 205°C|
|Standard||To BS 6351 Grade 2,2|
Rated Voltage – 220V/240V or 110V/120V AC/DC. Heater Zone (according to design) – 0,5/1,0m.
A 30mA trip Residual Current Circuit Device (RCCB) or Earth Leakage Circuit Breaker (ELCB) is recommended for use with heating tapes.
To calculate heat loss per meter of pipe:
Heat lossesW/m = ∆tx kexLoss factor
∆t= Pipe temp. – Ambient temp.
ke = Thermalconductivity.
|Pipe NB (mm)||Thermal insulation thickness (mm)|
To comply with BS 6351 allowance should be taken of maximum heater resistance tolerance(± 10%) and voltage variation(± 6%) = 1,1/(0.94)²= 1,25 x Heatloss.
A further design factor of 10% may be added.