Heated hoses
Heated hoses – general information
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.
Base hose
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.
Hose construction
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.
Fittings
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.
Thermal insulation
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
End caps
End caps come in two varieties: hard and soft. Polyamide hard caps reduce the free, flexible length of the hose between the fittings, but also reduce the load on the place where the fitting connects to the hose. Soft caps made of elastomer are recommended for short hoses due to their flexibility.
Hard caps
Soft caps
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.
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.
List of products:
Electrically heated hoses
Hoses heated by a heating agent
Analytical hoses for flue gas analysers
PTFE hoses with helically wound heating hose
Rubber heated hoses
Twin heated hoses
If you need help choosing a product or haven’t found the right one?
FAQ – Heated hoses:
PT100 sensors are most common in heated hoses. In plastics processing, J-type thermocouples (Fe-CuNi) are also popular, sometimes K-type thermocouples (NiCr-Ni). NI120 sensors are often used in Hot Melt systems.
Yes. Each heated hose, depending on the material it is made of, has pressure correction factors that must be taken into account in the calculations. For example, a PTFE hose with a diameter of 8 mm, which has a maximum working pressure of 200 bar at room temperature, will operate at a maximum of 166 bar at +250°C (correction factor 0.83).
A heated hose is selected individually for each specific application. Therefore, in order to make the right selection, it is necessary to provide information about the medium, working pressure, temperature to be maintained, movements performed, supply voltage, required temperature sensor, and hose parameters such as diameter, length, and type of fittings.
Only specially designed heated hoses with heaters and sensors in “Ex” version can operate in explosive zones.
Electrically heated hoses are often used in extruders, Hot Melt machines, wrap-around machines, edge banders, as well as flue gas analysers.