Chapter 19 Appendices

Appendix 2 Compressed Air - Milk and Milk Product Contact Surfaces

Material

Filter Media
Air intake and pipeline filters shall consist of fibreglass, cotton flannel, wool flannel, spun metal, electrostatic material or other equally acceptable filtering media, which are non-shedding and which do not release to the air, toxic volatiles, or volatiles which may impart any flavour or odour to the product.

Disposable media filters shall consist of cotton flannel, wool flannel, spun metal, non-woven fabric, absorbent cotton fibre or suitable inorganic materials which, under conditions of use, are non-toxic and nonshedding. Chemical bonding material, contained in the media, shall be non-toxic, nonvolatile and insoluble under all conditions of use. Disposable media shall not be cleaned and reused.

Filter Performance
The efficiency of intake filters shall be at least 50 percent as measured by the National Bureau of Standards "Dust Spot method" using atmospheric dust as the test aerosol.

The efficiency of either air pipeline filters or disposable filters shall be at least 50 percent as measured by the DOP (dioctyl phthalate) test.

Piping
Air distribution piping, fittings and gaskets between the terminal filter and any product contact surface, shall be sanitary milk piping, except, where compressing equipment is of the fan or blower type. When the air is used for such operations, as removing containers from mandrels, other non-toxic materials may be used.

Fabrication and Installation

Air Supply Equipment
The compressing equipment shall be designed to preclude contamination of the air with lubricant vapours and fumes. Oil-free air may be produced by one of the following methods or their equivalent:

Use of carbon ring piston compressor
Use of oil-lubricated compressor with effective provision for removal of any oil vapour by cooling the compressed air
Water-lubricated or non-lubricated blowers

The air supply shall be taken from a clean air space or from relatively clean outer air and shall pass through a filter upstream from the compressing equipment. This filter shall be located and constructed so that it is easily accessible for examination, and the filter media are easily removable for cleaning or replacing. The filter shall be protected from weather, drainage, water, product spillage and physical damage.

Moisture Removal Equipment

If it is necessary to cool the compressed air, and aftercooler shall be installed between the compressor and the air storage tank for the purpose removing moisture from compressed air.

Filters and Moisture Traps
Filters shall be constructed so as to assure effective passage of air through the filter media only.

The air under pressure shall pass through an oil-free filter and moisture trap for removal of solids and liquids. The filter and trap shall be located in the air pipeline, downstream from the compressing equipment, and from the air tank, if one is used. Air pipeline filters and moisture traps, downstream from the compressing equipment, shall not be required where the compressing equipment is of the fan or blower type.

A disposable media filter shall be located in the sanitary air pipelines upstream from and as close as possible to each point of application or ultimate use of the air.

Air Piping
The air piping from the compressing equipment to the filter and the moisture trap shall be readily drainable.

The product check valve of sanitary design shall be installed in the air piping, downstream from the disposable media filter, to prevent backflow of product into the air pipeline, except that a check valve shall not be required if the air piping enters the product zone from a point higher than the product overflow level which is open to atmosphere.

The requirements of this section do not apply when the compressing equipment is of the fan or blower type. See illustrations depicting various air supply systems.

Note : For additional details, see 3 A Accepted Practices for Supplying Air Under Pressure in Contact with Milk, Milk Products and Product Contact Surfaces, Number 604-04.