Some HTST Definitions

ATMOSPHERIC PRESSURE
-- The force exerted on an area by the column of air above that area. Atmospheric pressure at sea level is 14.7 pounds per square inch.

BALANCE TANK
-- Raw product tank located at the start of a pasteurization system used to maintain a constant supply of product to the pasteurizer.

BOOSTER PUMP
-- A centrifugal pump placed in a pasteurizing system between the balance tank and the raw regenerator and capable of producing positive pressure in the raw regenerator.

BOURDON COIL (spring)
-- A sealed flat metal tube filled with a gas mixture that has been formed into a coiled spiral, located inside the recorder-controller. This spiral expands or contracts in response to the vapor pressure of the gas mixture. This coil is located on one end of the capillary tube with the recorder-controller temperature sensing bulb at the other.

CAPILLARY TUBE
-- A thin metal tube, containing a mixture of liquids with low vapor pressures, that connects the bourdon tube in the recorder-controller with the temperature sensor bulb located at the flow diversion device. This thin tube is usually protected by a flexible metal cable.

CENTRIFUGAL PUMP
-- A high speed pump that produces product flow due to the velocity increase of the liquid caused by the rotation of the pump impeller.

CONSTANT LEVEL TANK
-- See Balance Tank.

COOLING SECTION
-- The section of a heat exchanger (press) in which one of several non-toxic coolants flows in a counter current direction on the opposite side of a stainless steel plate of the pasteurized product.

DEFLECTOR PLATE
-- A stainless steel plate in the regenerator section of the press designed to change the direction of flow.

FLOW DIVERSION DEVICE
-- Either a single stem (one three-way valve) or dual stem device (two, three-way valves connected by a common yoke), designed to change the direction of product flow when working in conjunction with the recorder-controller. (FDD)

FLOW CONTROLLER
-- An instrument used in meter based systems which compares the flow signal from the flow transmitter to a set point and either controls the centrifugal pump speed or regulates a flow control valve downstream of the meter and centrifugal pump.

FLOW TRANSMITTER
-- An instrument used in meter based systems which converts signals from the magnetic flow meter to a 4- 20ma current.

FREQUENCY PEN
-- A solenoid actuated recording pen (located on the outer edge of the recording chart) that records the position of the flow diversion device in a continuous flow pasteurization system. This pen on a meter based system only records the flow diversion device position that has been electronically signaled by the flow recorder/controller.

HEAT EXCHANGER
-- Equipment designed to effect heat transfer between two or more mediums.(plate type, triple tubes, etc.).

HOLDING TUBE
-- The section of piping in continuous flow pasteurizers of sufficient length to provide the minimum legal residence time for heated milk.

HOT WATER TEMPERATURE CONTROLLER
-- A system which controls the temperature of the heating medium by regulating a mixture of steam and water that circulates through the heating section of the press.

I/P TRANSDUCER
-- An instrument used in a meter based system that converts a 4-20ma current signal to an air signal (usually 15-30 psi) which drives the flow recorder pen

LAMINAR FLOW
-- The movement of high viscosity products through a pipe in concentric layers where the fastest particle may move at twice the speed of the average particle

METERING PUMP
-- See Timing Pump

PNEUMATIC
-- Operated by compressed air.

REGENERATOR BY-PASS VALVE
-- A automatic or manually controlled valve used in combination with the booster pump for the purposes of start up of a continuous pasteurizer with a milk to milk regenerator. This valve allows for by-passing the regenerator in order to provide the proper pressure relationships in the regenerator, thus allowing the booster pump to operate.

SANITIZATION
-- The application of any effective method or substance to a clean surface for the destruction of pathogens, and of other organisms as far as is practicable. Such treatment must not adversely affect the equipment , the milk or milk product or the health of consumers. Sanitization may be accomplished by either the application of heat or suitable chemicals used in accordance with good manufacturing practices.

SAFETY THERMAL LIMIT CONTROLLER
-- The term sometimes used interchangeably when referring to the recorder-controller.

SOLENOID
-- An electronically operated valve used in various air controlling applications on continuous pasteurizers.

STUFFING PUMP
-- Any centrifugal pump used in the system for the purposes of enhancing product flow to a component, other that those located between the balance tank and the raw regenerator.

TIME DELAY RELAY (TDR)
-- An adjustable timer(either mechanical or electronically controlled) used to maintain a set time period equal to or greater than the required minimum. All required TDR's must be sealed by the regulatory agency.

TIMING PUMP
-- Sanitary , positive displacement -type (rotary or piston) or in the case of meter based systems a centrifugal product pump, which provides a constant measured rate of flow to the continuous pasteurization system.

TURBULENT FLOW
-- Flow where considerable mixing occurs across a pipe cross section and the velocity is nearly the same across this section. Turbulent flow occurs most frequently in less viscous liquids and is often characterized by higher friction losses than would be expected.

VACUUM BREAKER
-- An air relief valve held in the closed position by product flow pressures and which opens and admits air when the product pressure goes