provided per manufacturer. When a bed depth is less than fifteen inches, filters shall be designed to operate at no more than twelve gallons per minute per square foot. 2. The design filtration rate for surface-type cartridge filters shall not exceed three-tenths gallons per minute per square foot. One complete set of spare cartridges shall be maintained on site in a clean and dry condition. 3. The design filtration rate for pre-coat filters shall be based on the following types: (i) Vacuum pre-coat filters not be more than either two gallons per minute per square foot, or two and one half gallons per minute per square foot when used with a continuous pre-coat media feed. (ii) Pressure pre-coat filters shall not be more than two gallons per minute per square foot of effective filter surface area. (iii) The filtration surface area shall be based on the outside surface area of the media with the manufacturer's recommended thickness of pre-coat media and consistent with their NSF Standard 50 listing and labeling. (c) Filters be designed so that filtration surfaces can be inspected and serviced. (d) Alternate types of filter media shall be listed and labeled to NSF Standard 50. (2) Internal Pressure. On pressure-type filters, a shall be provided to permit the release of internal pressure. (a) Any filter incorporating an automatic internal air release as its principal of air release shall have lids which provide a slow and safe release of pressure as a part of its design. Rule .08(2)
provided per manufacturer. When a bed depth is less than fifteen inches, filters shall be designed to operate at no more than twelve gallons per minute per square foot. 2. The design filtration rate for surface-type cartridge filters shall not exceed three-tenths gallons per minute per square foot. One complete set of spare cartridges shall be maintained on site in a clean and dry condition. 3. The design filtration rate for pre-coat filters shall be based on the following types: (i) Vacuum pre-coat filters not be more than either two gallons per minute per square foot, or two and one half gallons per minute per square foot when used with a continuous pre-coat media feed. (ii) Pressure pre-coat filters shall not be more than two gallons per minute per square foot of effective filter surface area. (iii) The filtration surface area shall be based on the outside surface area of the media with the manufacturer's recommended thickness of pre-coat media and consistent with their NSF Standard 50 listing and labeling. (c) Filters be designed so that filtration surfaces can be inspected and serviced. (d) Alternate types of filter media shall be listed and labeled to NSF Standard 50. (2) Internal Pressure. On pressure-type filters, a shall be provided to permit the release of internal pressure. (a) Any filter incorporating an automatic internal air release as its principal of air release shall have lids which provide a slow and safe release of pressure as a part of its design. Rule .08(2)