Air conditioning hose is used for automotive or domestic air conditioning
system. It is a textile-reinforced rubber hose with a thick inner
liner. It can be single braided with reinforcement layer of rayon
or similar textile or it can be a two textile braided layers, separated
from each other by a layer of bonded rubber compound. Both types have
an outer cover, which is pricked to allow any refrigerant gas that
has permeated through the reinforcement layer to escape without causing
the hose to blister. It can also be made with a wire-reinforced with
an inner liner, a wire reinforcement layer, and an outer layer of
heat-resistant textile reinforcement.
Multilayers air conditioning tubing are made of innerlayer of HNBR,
intermediate layer of Butyl rubber and outer layer of EPDM. The three
compounds were optimised for bonding, physical properties and cure
characteristics.
A sample of air conditioning hose can be described as having the
following dimensions:
It has a length of 54 cm from end to clip end, an internal diameter
(ID) of 11 mm, middle diameter (MD) of 17mm and outer diameter (OD)
of 21mm.
Method Of Production
- Preparation of rubber compounds
- Preparation of rubber strips
- Extrusion of inner liner (rubber strips)
- Passing of inner liner through a textile braiding machine
- Extruding the cover over the braided tubing
- The unvulcanised hose is chopped to a required length, then
inserted onto a lubricated mandrel
- Vulcanisation is carried out continuously in Microwave heating,
LCM, Fluidised Bed or batchwise it can be cured using high pressure
steam in autoclave.
- Trimming
- Any branches or T-pieces required in the coolant hose can be
fabricated before vulcanisation
- For shaping, hose are normally partially vulcanised and put
onto the lubricated shaped mandrel, where vulcanisation is completed
and the desired shape is achieved. Broadly speaking braided hose
is made by one of three basic processes:
(a) hose made on steel mandrels
(b) hose made on flexible mandrels
(c) hose in which the braided yarn is applied to an unsupported
lining
- as in case of long-length lead-pressed
hose.
|
