Heated hoses are designed for applications where the medium passing through the hose must be heated, melted but first of all, maintained at constant, elevated temperature. It usually concerns: oil, grease, wax, resins, hot melt adhesives, paints, granulates, food products. There are two groups of heated hoses – electrically heated hoses and hoses heated with a heating agent (heating oil, steam.) The heated hoses are made using PTFE, steel and sometimes rubber hose as a base hose.
Electrically Heated Hoses
ETH, Electrically Trace Heated hoses are intended for the transfer, loading and unloading of substances that conveyed through the hose, must be heated, melted and kept at constant, elevated temperature. Application for such media as: oil, grease, wax, resins, hot melt adhesives, paints, granules, food products. They are extensively used for hot melt adhesive dosing. Optionally manufactured as EX approved, according to ATEX directive for use in potentially explosive atmospheres. There is also a heated twin hose designed specifically for polyurethane foam production and hoses for exhaust analysis systems.
Electrically heated hoses are composed of:
- base hose (hose assembly) with fittings, resistant to pressure, temperature and medium flowing through;
- heating element and temperature sensor;
- thermal insulation;
- outer cover and hose end caps;
- connecting cable, plug and temperature controller.
The base hose is chosen depending on the working pressure and medium output required. PTFE hose in stainless steel braid is the most common. The material of this hose features outstanding chemical and temperature resistance (up to 250°C), and very low coefficient of friction. At temperatures above 250°C steel hoses are used.
The hose fittings (threaded, pipe or flange) at both hose ends are selected according to customer’s specification. Tubes International supplies the electrically trace heated hoses with virtually all types of fittings available on the market.
Heating element and temperature sensor
Heating element and temperature sensor are helically wound around the base hose. The power of the heating element depends on the temperature that must be maintained, the diameter and length of the hose. Supply voltage is usually 230 V (optionally 12 ÷ 500 V). As a standard temperature sensors of PT100 type are used, type J and K thermocouples, though other sensors are also available, e.g. NI120, NTC.
The type of thermal insulation depends on working temperature. Elastomer foam is used for temperatures up to 100°C, silicone foam up to 250°C, fibreglass insulation for higher temperatures.
Outer cover and hose end caps
Polyamide braid is usually applied as the outer cover, but steel braid, polyurethane braid, silicone braid or fibreglass braid are also available. There are two hose end cap options: hard and soft. The hard caps made of polyamide reduce free, flexible hose length between the fittings, but also reduce the load on the spot of critical fitting-hose connection. Elastomer soft caps, due to their flexibility, are recommended for short hoses.
|Standard polyamide braid||Corrugated polyurethane hose||Fibreglass braid||Corrugated polyamide hose|
|Stripwound metal hose||Steel braid||Silicone rubber braid|
Connecting cable, plug and temperature controller.
The electrically heated hose is equipped with a connecting cable e.g. 1,5 m long with or without plug. The hoses can be used with a temperature controller of the customer or supplied with various types of temperature controllers including the simplest mini controllers built into the hose but also multi-channel controllers serving several hoses.
Apart from the standard heated hoses, Tubes International offers the following hoses:
|Rubber electrically heated hoses (ETH HL 80)||Twin electrically heated hoses (TWIN)|
|Electrically heated hoses intended for operation in potentially explosive atmosphere (EX)||Analytical heated hoses – exhaust gas analysis (AN)|
Rubber hoses with an integrated heating system
The electrically heated rubber hoses make a group of very peculiar hoses – the heating element is wound onto the internal rubber hose layer and vulcanized. The temperature sensor reads the temperature directly in the hose wall. The hose is not visually different from a standard rubber hose. These hoses (e.g. made of NBR rubber) are used particularly in food industry to transfer fats and other food products.
CORROFLON and BIOFLEX ULTRA PTFE electrically heated hoses
They are made using excellent CORROFLON or BIOFLEX ULTRA PTFE process hoses as a base hose. These hoses may be equipped with fittings with PTFE liner extended through the fitting and flared out on the sealing face. Used in the food industry and for loading/unloading of hazardous chemical substances.
Hoses heated with a heating agent
Hoses heated with a heating agent (steam, hot water, heating oil) are intended for the transfer, loading and unloading of substances that conveyed through the hose, must be heated, melted and kept at constant, elevated temperature. Application for such media as: oil, grease, wax, resins, paints, granulates, chemical substances, adhesives, food products They can substitute electrically heated hoses in applications where such heating agents as technological steam or heating oil are easily accessible or where electrical power supply is not acceptable or not recommended. Frequently used for the loading/unloading of rail tankers, operation in potentially explosive atmospheres is also possible.
A braided PTFE or steel hose is used as a base hose. A heating hose (PTFE or of other plastic material) is wound around this hose. The hose assembly has thermal insulation layer, outer cover and end caps. The inlet and outlet of the heating hose can be on one side or on both sides of the hose assembly.
Excellent CORROFLON or BIOFLEX ULTRA PTFE process hoses are available as CH version as well. These hoses may be equipped with fittings with PTFE liner extended through the fitting and flared out on the sealing face. Used in the food industry and for loading/unloading of hazardous chemical substances.
There is also another heated hose type, a jacketed hose (a double steel hose – the base hose is in the outer heating hose, a jacket). These hoses are made using metal pressure hoses.