(1) Temperature difference. The pasteurizer shall be so designed that the simultaneous temperature difference between the milk or milk product at the center and the coldest milk or milk product in the vat will not exceed a margin of one degree Fahrenheit (one-half degree Celsius) at any time during the holding period. The vat shall be provided with adequate agitation, operating throughout the holding period. No batch of milk or milk product shall be pasteurized unless it covers a sufficient area of the agitator to insure adequate agitation.

(2) Location and required readings of indicating and recording thermometers. Each batch pasteurizer shall be equipped with both an indicating and a recording thermometer. The thermometers shall read not less than the required pasteurization temperature throughout the required holding period. The plant operator shall check daily the temperature shown by the recording thermometer against the temperature shown by the indicating thermometer; this comparison shall be noted on the recording thermometer chart. The recording thermometer shall not read higher than the indicating thermometer. No batch of milk or milk products shall be pasteurized unless it is sufficient to cover the bulbs of both the indicating and the recording thermometers.

(3) Assurance of minimum holding periods. Batch pasteurizers shall be so operated that every particle of milk or milk product will be held at not less than the minimum pasteurization temperature continuously for at least 30 minutes. When milk or milk products are raised to pasteurization temperature in the vat, and cooling is begun in the vat, simultaneously with or before the opening of the outlet valve, the recorder chart shall show at least 30 minutes at not less than minimum pasteurization temperature. When milk or milk products are preheated to pasteurization temperature before entering the vat, the recorder chart shall show a holding period of at least 30 minutes at not less than the minimum pasteurization temperature plus the time of filling from the level of the recorder bulb. When cooling is begun in the holder after the opening of the outlet valve, or is done entirely outside the holder, the chart shall show at least 30 minutes at not less than the minimum pasteurization temperature plus the time of emptying to the level of the recording thermometer bulb. When the recorder time interval on the recorder chart at the pasteurization temperature includes filling and/or emptying time, such intervals shall be indicated on the recorder chart by the operator, by removing the recording thermometer bulb from the milk for a sufficient time to depress the pen, or by turning cold water into the vat jacket at the end of the holding period, or by inscribing the holding time on the chart. The filling time and the emptying time for each holder so operated shall be determined by the commissioner, initially and after any change which may affect these times. No milk shall be added to the holder after the start of the holding period.

(1) Means shall be provided and used in batch pasteurizers to keep the atmosphere above the milk and milk products at a temperature not less than five degrees Fahrenheit (three degrees Celsius) higher than the minimum required temperature of pasteurization during the holding period (Appendix 3 of this Title).

(2) Each batch pasteurizer shall be equipped with an airspace thermometer. The surface of the milk or milk product shall be at least one inch below the bottom of the thermometer bulb when the vat is in operation.

(3) The temperature shown by the airspace thermometer shall be recorded on the recording thermometer chart each time the pasteurizer is in operation.

(1) Valve stop shall mean a guide which permits turning the valve plug to, but not beyond, the fully closed position.

(2) 90° stop shall mean a stop so designed as to prevent turning the plug more than 90 degrees.

(3) 120° stop shall mean a stop which prevents turning the plug more than 120 degrees.

(4) 180° stop shall mean a stop which prevents turning the plug more than 180°, but which permits two fully closed positions, each diametrically opposite the other.

(5) Valve with an irreversible plug shall mean one in which the plug cannot be reversed in the shell.

(6) Single-quadrant stop shall mean a 90-degree stop in a valve with an irreversible plug.

(7) The fully open position shall mean that position of the valve seat which permits the maximum flow into or out of the pasteurizer.

(8) The closed position shall mean any position of the valve seat which stops the flow of milk into or out of the pasteurizer.

(9) The fully closed position shall mean that closed position of the valve seat which requires the maximum movement of the valve to reach the fully open position.

(10) The just-closed position shall mean that closed position of a plug-type valve in which the flow into or out of the holder is barely stopped, or any closed position within 0.078 inch thereof as measured along the maximum circumference of the valve seat.

(11) Leakage shall mean the entrance of unpasteurized milk onto a batch pasteurizer during the holding or emptying period, or the entrance of unpasteurized milk into any pasteurized milk line at any time.

(12) Leak-protector valve shall mean a valve provided with a leak-diverting device, which, when the valve is in any closed position, will prevent leakage of milk past the valve or, in the case of batch pasteurizers filled or emptied by suction or compressed air, will prevent leakage of milk past the valve or the leakage of milk due to the leakage of air past the suction valve or the compressed air valve, as the case may be.

(13) Closed-coupled valve shall mean a valve, the seat of which is either flush with the inner wall of the pasteurizer, or so closely coupled that no milk in the valve inlet is more than one degree Fahrenheit (one-half degree Celsius) colder than the milk at the center of the pasteurizer at any time during the holding period. A close-coupled valve which is not truly flush shall be considered as satisfying this requirement when:

(1) Valves and pipeline connections shall meet the requirements of section 2.38 of this Part (Item 10p).

(2) All pipelines and fittings shall be so constructed and so located that leakage will not occur. Dependence shall not be placed on soldered joints to prevent leakage.

(3) To prevent clogging, and to promote drainage, all leak-protector grooves shall be at least 0.187 inch wide, and at least 0.094 inch deep at the center. Mating grooves shall provide these dimensions throughout their combined length whenever the valve is in, or approximately in, the fully closed position. All single-leak grooves, and all mating leak grooves when mated, shall extend throughout the entire depth of the seat, so as to divert leakage occurring at all points throughout the depth of the seat, and so as to prevent air bindings. Washers or other parts shall not obstruct leak-protector grooves.

(4) A stop shall be provided on all plug-type outlet valves and on all plug-type inlet valves in order to guide the operator in closing the valve so that unpasteurized milk may not inadvertently be permitted to enter the outlet line or the holder, respectively. The stop shall be so designed that the plug will be irreversible when the plug is provided with any grooves or their equivalent, unless duplicate, diametrically opposite grooves are also provided. In the case of two-way, plug-type valves (i.e., those having only one inlet and one outlet), a 180-degree stop, or any combination of stops permitting two fully closed positions, may be substituted for a 90-degree stop, provided that there are no air-relief grooves in the plug and that all leak grooves are located symetrically with respect to the valve inlet. Stops shall be so designed that the operator cannot turn the valve beyond the stop position, either by raising the plug or by any other means.

(5) Outlet valves, in addition to the requirements listed above, shall be so designed as to prevent the accumulation of unpasteurized milk in the milk passages of the valve when the valve is in any closed position.

(6) All inlet pipelines and outlets from vat pasteurizers shall be equipped with leak-protector valves; provided, that installations not equipped with leak-protector inlet valves shall be accepted when the piping is so arranged that only one vat can be connected to the inlet line at a time, and such piping is disconnected during the holding and emptying periods.

(7) Inlet and outlet connections other than through closed-coupled valves shall not enter or leave the pasteurizer below the level of the milk therein.

(8) In cases where the inlet line enters the holder above the milk level, and in which the inlet line may be submerged and thus prevent its complete emptying when the inlet valve is closed, the inlet line shall be provided with an automatic air-relief, or vent located either at the valve or elsewhere, and so designed as to function in every closed position of the valve. A vent may be provided by drilling a hole at least 0.125 inch in diameter in the vat pipe, below the vat cover, but above the maximum milk level.

(9) All leak-protector valves shall be installed in the proper position to insure the function of the leak-diverting device. Inlet valves shall not be located in vertical pipelines, unless they can be so installed that one of the groove systems is at the lowest level of the valve; and pipelines between the inlet valve and the pasteurizer shall be as short as practicable and shall be so sloped to drain.

(10) All outlet valves shall be kept fully closed during filling, heating and holding periods; and all inlet valves shall be kept fully closed during holding and emptying periods.