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Rubber Hose
The three most popular rubber steam
hoses that we supply are:
Steam hose used in food and beverage plants is available with non marking coloured covers, usually white or blue. A range of steam lances is
also available.
Saturated Steam / Superheated Steam
There is a temperature / pressure relationship as shown in the following chart with regard to saturated steam.
|
Gauge Pressure |
Temperature |
|
Psi |
Bar |
Celsius |
|
25 |
1.73 |
130 |
|
35 |
2.42 |
138 |
|
50 |
3.45 |
144 |
|
80 |
5.52 |
162 |
|
100 |
6.90 |
170 |
|
140 |
9.66 |
182 |
|
180 |
12.42 |
193 |
|
200 |
13.80 |
198 |
|
225 |
15.53 |
203 |
|
250 |
17.58 |
208 |
|
275 |
18.98 |
212 |
|
300 |
20.70 |
216 |
The temperature of saturated steam is always in accordance with the pressure, since the boiling point, and conversely, the condensation point of the water - steam system is governed by the pressure. However, if additional heat energy is put into the system after the water has been converted to dry saturated steam, the temperature of the steam rises above that of its boiling condensing point for the ruling pressure, and steam in this condition is known as superheated steam and thus superheated steam does not follow any fixed temperature / pressure relationship.
Lining Deterioration of steam hose
Steam hose linings often fail by blistering, pelletising or delaminating. Rubbers are to some extent permeable and steam in the gaseous phase permeates into the hose wall. When the steam is turned off, the steam in the rubber condenses and the tiny droplets are trapped. When steam flow recommences, this trapped moisture vaporizes, increases in volume dramatically and literally explodes causing what is known as the popcorn effect, i.e. leaving smooth concave indentations in the hose lining. Frequent changes in temperature accelerate this process especially where the steam is wet. For this reason, we recommend that wherever practical the hose should always be drained after use.
Reinforcement deterioration
Steam hoses may be reinforced either with textile or wire strands. For working pressures in excess of 100 psi, wire is almost always used. High temperatures cause the nylon reinforcement used in steam hoses to lose strength over time and even the wire reinforcement can be corroded if steam is generated which is either acidic or containing free oxygen. As this deterioration is not visible, it is absolutely essential to have in place a system of inspection and scheduled replacement.
Fittings
Only fittings designed for use with steam hose should be used and should always be attached by clamps using nuts and bolts and never by swaged ends. The clamps should always be tightened before the hose is used. Needless to say, selection of the correct clamp dimensions is critical. Advice is available from Parkland on all these matters.
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