Question

The hose having an inner lining with vulcanized rubber is
1. Reeled
2. Percolating
3. Non-percolatin
4. Embedded

Answer 1

Correct Answer - Option 3 : Non-percolatin

Explanation:

• Percolating hose may be made from natural fibre, or synthetic fibre, or blends of both which may be unlined or lined with natural or synthetic material or vulcanized natural rubber lining.
• Percolating hose is generally lighter than non-percolating hose of the same size, and because water seeps through the jacket, the hose provides a degree of self-protection against embers and flame when in use.
• For this reason percolating hose is not subject to the heat test.
• Further, the abrasion test cannot be satisfactorily carried out on a wet jacket and is not applied to percolating hose.
• The rate of percolation in a natural fibre hose is controlled by the swelling of the fibres as they absorb water.
• Because synthetic fibres have a lower water absorption, the rate of percolation is controlled by a thin lining.
• The prime reason for using non-percolating hose is to minimize water damage to property from seepage.
• It may be used for the application of foam.
• Because the lining is thicker than in a percolating hose, the inner surface is smoother, resulting in lower pressure losses due to friction.
• Where resistance to abrasion or chemical attack is a factor, coated non-percolating hose should be considered.