Sec. 3.25. High-temperature-short-time, (HTST), continuous-flow pasteurization—Item 16p(A)

(a) Indicating thermometers and recorder/controller instruments.

All indicating thermometers and recorder/controller instruments and devices used in connection with the high-temperature-short-time, continuous-flow pasteurization of milk, milk products, whey, condensed milk products and condensed whey shall comply with the applicable specifications set forth in Appendix 9 of this Title.

(b) Automatic milk controller.

Each high-temperature-short-time, continuous-flow pasteurization system shall be equipped with an automatic milk flow control of the diversion type which complies with the following:

(1) Automatic milk flow controls. The term automatic milk flow controls shall mean those safety devices which control the flow of product in relation to the temperature of the product, heating medium, pressure, vacuum or other auxiliary equipment. Milk flow cntrols shall not be considered a part of the temperature control equipment. Milk flow controls shall be of the flow-diversion type which automatically cause the diversion of subtemperature product. Flow-diversion devices shall return the subtemperature product to the raw product side of the heating system continuously until proper pasteurization temperatures are obtained, at which time the device shall restore forward product flow through th pasteurizer.

(2) Flow-diversion devices. Flow-diversion devices used in continuous pasteurizers shall comply with the following:

(i) Forward flow of subtemperature product due to the omission or looseness of the connecting clip shall be prevented by making the valve and its actuating mechanism integral, or, where there is a connecting device, by making it impossible to assemble the valve and its actuating mechanism except in such manner that it will function properly, or, where there is a connecting device which may be omitted or shaken loose, by providing for pushing, instead of pulling, the valve to the diverted position; or by providing that the pump will shut down when the product is below the pasteruization temperature and the valve is not in the fully diverted position, or by other satisfactory means.

(ii) A packing gland, used to prevent leakage around the actuating stem, shall be constructed so as to prevent tightening of the stem packing nut to such an extent as to prevent the valve from assuming the fully diverted position.

(iii) A leak escape shall be installed on the forward-flow side of the valve seat. However, when back pressure is exerted on the forward-flow side of the valve seat while the product flow is being diverted, the leak escape should lie between two valve seats or between two portions of the same seat, one upstream and the other downstream from the leak escape. The leak escape shall be designed and installed to discharge all leakage to the outside or to the constant-level tank through a line separate from the diversion line, provided that, when leakage is discharged to the constant-level tank, a sight glass shall be installed in the leak escape line to provide visual means of leak detection.

(iv) The closure of the forward-flow seat shall be sufficiently tight so that leakage past it will not exceed the capacity of the leak escape device, as evidenced when the forward-flow line is disconnected. The length of the connecting rod shall not be adjustable by the user.

(v) The flow-diversion device shall be designed and installed so that failure of the primary motivating power shall automatically divert the flow of product.

(vi) The flow-diversion device shall be located downstream from the holder. The flow-control sensor shall be located in the product line not more than 18 inches upstream from the flow-control device.

(vii) The pipeline from the diversion port of the flow-diversion device shall be self-draining and shall be free of restrictions or valves, unless such restrictions or valves are designed so that stoppage of the diversion line cannot occur.

(viii) The pipeline from the leak detector part of the flow-diversion device shall be self-draining and shall be free of restrictions or valves, unless such restrictions or valves are designed so that stoppage of the leak detector line cannot occur.

(3) Milk flow controller instrumentation. Instrumentation of the milk flow controller shall comply with the following:

(i) The thermal limit controller shall be set and sealed so that forward flow of product cannot start unless the termperature at the controller sensor is above the required pasteurization temperature, as defined in section 3.2(k) of this Part, for the milk, milk product, whey, condensed whey and the process used. The thermal unit controller shall be set and sealed so that forward flow of product cannot continue during descending temperatures when the product temperature is below the required pasteurization temperature. The thermal limit controller shall be sealed by the regulatory agency after testing, and the seal shall not be removed without immediately notifying the regulatory agency. The system shall be designed so that no product can bypass the controller sensor. The controller sensor shall not be removed from its proper position during the pasteurization process. The cut-in and cut-out product temperatures, as shown by the indicating thermometer, shall be determined at the beginning of each day's operation and entered upon the recorder chart daily by the plant operator.

(ii) Manual switches for the control of pumps, homogenizers or other devices which produce flow through the holder shall be wired so that the circuit is completed only when the product is above the required pasteurization temperature, as defined in section 3.2(k) of this Part, for the milk, milk product, whey, condensed milk products and condensed whey and the process used, or when the diversion device is in the fully diverted position.

(4) Holding tube.

(i) Holders shall be designed to provide for the holding of every particle of product for at least the time required in section 3.2(k) of this Part for the milk, milk product, whey, condensed milk products and condensed whey and the process used.

(ii) The holder shall be so designed that the simultaneous temperature difference between the hottest and coldest product in any cross-section of flow at any time during the holding period will not be greater than one degree Fahrenheit (one-half degree Celsius). Tubular holders, seven inches in diameter or smaller, which are free of fittings may satisfy this requirement without test.

(iii) No device shall be permitted for short-circuiting a portion of the holder to compensate for changes in rate of product flow. Holding tubes shall be installed so that sections of pipe cannot be left out (thus resulting in a shortened holding time).

(iv) The holding tube shall be arranged to have a continuous upward slope in the direction of flow of not less than 0.25 inch per foot.

(v) Tube supports shall be provided to maintain all parts of holding tubes in a fixed position, free from any lateral or vertical movement.

(vi) The holder shall be designed so that no portion between the inlet and the flow-control temperature sensor is heated.

(5) Indicating and recording thermometers.

(i) An indicating thermometer shall be located as near as practicable to the temperature sensor of the recorder/controller.

(ii) The termperature shown by the recorder/controller shall be checked daily by the plant operator against the temperature shown by the indicating thermometer. Readings shall be recorded on the chart. The recorder/controller shall be adjusted to read no higher than the indicating thermometer.

(iii) The recorder/controller charts shall comply with the applicable provisions of section 3.27 of this Part (Item 16p[C]).

(6) Flow-promoting devices.

(i) The pump, or pumps, and other equipment which may produce flow through the holder shall be located upstream from the holder, provided that pumps and other flow-promoting devices may be located downstream from the holder if means are provided to eliminate negative pressure between the holder and the inlet to such equipment. When vacuum equipment is located downstream from the holder, an effective vacuum breaker and an automatic means of preventing a negative pressure in the line between the flow-diversion device and the vacuum chamber shall be acceptable.

(ii) The speed of pumps or other flow-promoting devices governing the rate of flow through the holder shall be controlled so as to insure the holding of every particle of product for at least the time required, as defined in section 3.2(k) of this Part, for the product and the process used. The pump motor shall be connected to the metering pump by a common drive shaft, or by gears and pulleys, or by a variable-speed drive, with the gear box, the pulley box, or the setting of the variable speed protected in such a manner that the holding time cannot be shortened without detection by the regulatory agency. Pumps shall be sealed after tests by the regulatory agency and such seal shall not be broken without immediately notifying the regulatory agency. This provision shall apply to all homogenizers used as timing pumps. Variable-speed drives used in connection with the metering pump shall be constructed so that wearing or stretching of the belt results in a slowdown, rather than a speedup, of the pump. The metering or timing pump shall be of the positive displacement type.

(iii) The holding time shall be taken to mean the flow time of the fastest particle of product, at or above the required pasteurization temperature, as defined in section 3.2(k) of this Part, for the product and the process used, throughout the holder section. The holder section is that portion of the system that is outside of the influence of the heating medium which slopes continuously upward in the downstream direction and is located upstream from the flow-diversion device. Tests for holding time shall be made when all equipment and devices are operated and adjusted to provide for maximum flow. When a homogenizer is located upstream from the holder, the holding time shall be determined with the homogenizer in operation with no pressure on the homogenizer valves. Where bypass lines are provided, either upstream or downstream from the metering pump, the holding time shall be tested with both the regular and bypass line open unless the bypass valve is so designed that both lines cannot be open at the same time. The holding time shall be tested during both forward and diverted flow. If necessary to lengthen the holding time during diverted flow, an identifiable restriction may be placed in the vertical portion of the diversion pipeline. When vacuum equipment is located downstream from the holder, the holding time shall be tested with the metering pump operating at maximum flow, and the vacuum equipment adjusted to provide for the maximum vacuum. The holding time shall be tested in both forward and diverted flow by the regulatory agency initially and quarterly thereafter. After any alteration or replacement that may affect the holding time, and whenever the seal of the speed setting has been broken, the holding time shall be tested by the regulatory agency.