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
Corrugated polyamide hose
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.
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.