The internal lining of portable fire extinguishers by spraying (picture)

GUIDE TO TYPICAL COATING CONDITIONS

Ensure metal is clean by thorough degreasing by use of an aqueous degrease system and removal of rust and mill scale by grit-blasting to SA 2 2½-3. If there is no mill scale an aqueous phospho-degrease system can be used. The cylinders must be empty of excess water after pre-treatment and should be coated within 24 hours.

Pre-heat cylinder to 240°C - 260°C.

Spray powder for 30 to 40 secs depending on size of cylinders

The coating weight for a 9 litre cylinder is approximately 200-240g.

The coating weight for a 6 litre cylinder is approximately 140-200g.

Typical thicknesses are:

500 microns over smooth surfaces and 800-1000 microns over welds.

The process temperature used should be the minimum to achieve an continuous surface finish (see below).

Preheat: 1.5 mins
Typical Metal Temperature between 240°C and 280°C
Dwell: 30 seconds
Postheat: 30 seconds

The typical shot weight for a 9 litre cylinder is 360 to 410g depending on the cylinder design and for a 6 litre cylinder is 300 g.

This produces a coating thickness of around 1mm.
 

If iron phosphate is being used the preheat temperature should be kept below 260° C. The process temperature used should be the minimum to achieve an continuous surface finish (see below).

Usually, a (red) polyester coating is electrostatically applied to the outside of the cylinders after the internal lining has been applied. When the internal lining has been correctly applied, Plascoat PPA 665XL withstands the polyester curing cycle of 20 minutes at 185-220°C without problems and the lining becomes smooth.

Notes:

Overheating may cause the coating to discolour later in storage or in service.

Thicknesses outside the recommended range may be detrimental to the properties of the coating.

Stored in a clean, dry area at ambient temperature the material will not deteriorate. However, in the interest of good housekeeping, stocks should be rotated.

Plascoat PPA 665XL is supplied as a finely divided powder. Whilst there are no known health hazards associated with PPA 665XL, normal handling precautions for dealing with fine organic powders should be taken - i.e. excessive dust generation and inhaling of the powder should be avoided. Facilities may be required for removing excess dust from the working area during the coating of certain difficult items.

As with all polymeric powders, the material can ignite if brought into contact with a high temperature source or ignition - particularly in the fluidised condition.

Reference should be made to Plascoat Health and Safety Data Sheet HS512, available on request.

Direct 23°C

2.8 Joules

H18, 500g load, 1000 cycles

50 mg weight loss

Steel - scribed - 1000hrs

Steel - unscribed

 Loss of adhesion <10mm from scribe

Under-film corrosion <0.5mm

(A phosphated substrate will improve corrosion resistance)

No blistering or corrosion

- Dilute Alkali 60°C

- Salts (except peroxides) 60°C

- Ethylene glycol - 30% @ 50°C

- Solvents 23°C

Good

Good

Good

Not recommended