Page 52 - 2010-2022 hose manufactureing ability and guide

TOLERANCES

Chapter 4

Dimensional tolerances attainable in hose are determined by the method of manufacturing. The
tolerances given in this handbook are those which have been found practical in commercial usage
and are satisfactory for the installation on hose of fittings and couplings and for security of
attachment in service under normal circumstances.
Customers requiring use of zero defects acceptance sampling plans should understand that this
will necessitate special handling and sorting procedures to attain the desired level of acceptance.
Likewise, the requirement of tolerances tighter than those given will necessitate special handling and
sorting procedures.
Most hose produced by conventional methods has good length stability and falls within the length
tolerances shown in this chapter. However, some types of hose have a tendency to shrink or shorten
more than normal during shipment or storage. This is especially true of hoses made with a helical
wire embedded in the carcass. Consequently, the actual length should be determined by measuring
under 10 psi (0.07 MPa) hydrostatic pressure. When these hoses are subjected to a nominal pressure,
they generally will elongate to their original shipping length.

Class Identification Second
In order to provide for a quick and easy Digit Description
means of identifying the proper tolerances as set 1 Steel Mandrel
up by manufacturing methods, a code of three 2 Flexible Mandrel
numbers with a letter has been devised. The first 3 Non-Mandrel- Mold cured
digit identifies the product by the broad general 4 Non-Mandrel- Non-Mold cured
description of its method of manufacture. These
numbers and their descriptions are as follows: The third digit distinguishes, where
necessary, between tolerances on hose made
First with rubber cover as opposed to hose which is
Digit Description made without a rubber cover but with a cement
1 Textile — Braided, knitted or spiral protection. These numbers and their
wound descriptions are as follows:
2 Wire — Braided or spiral wound
3 Machine made — Wrapped or Third
spiralled ply Digit Description
4 Hand built — Non-wire reinforced 1 No distinction between hose
5 Hand built — Wire reinforced 2 Applies to rubber covered only
6 Circular woven — Fire hose 3 Applies to non-rubber covered only
7 Circular woven — Chernack Loom
8 Dredging Sleeves
The letter “A” designates that these are
commercial tolerances.
The second digit identifies the product by
subdivisions of its method of manufacture.
These numbers and their descriptions are as
follows:

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