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U. S. Food and Drug Administration
Center for Food Safety and Applied Nutrition
FDA Prime Connection
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M-I-85-8 - Questions and Answers from HTST Train. Course
HHS/PHS/FDA/CFSAN/OC/DCP/MSB
200 ~C~ Street, S.W.
Washington, D.C. 20204
M-I-85-8
August 6, 1985
TO: All Regional Food and Drug Directors
Attn: Regional Milk Specialists
FROM: Milk Safety Branch (HFF-346)
SUBJECT: Questions and Answers from HTST Training Course
Enclosed are copies of questions and answers presented as a result of a
HTST Training Course in Region VII.
Copies are enclosed for distribution to the State milk sanitation regulatory
agencies and State milk rating officers in your Region.
Robert L. Sanders
Deputy Chief, Milk Safety Branch
Division of Cooperative Programs
Center for Food Safety and
Applied Nutrution
______________________________________________________________
From: Milk Safety Branch, HFF-346
Subject: Questions/issues from HTST Training Course, M-I-85-8
To: R.W. Wilson, Senior Regional Milk Specialist, Region VII,
HFR-715
This is in response to your recent memo concerning the
above subject:
1.Q. Constant Level Tank (CLT) - being higher than the bottom of the
press with an automatic valve which dumps to the floor, thus
allowing the regenerator to drain. This does not sound bad at first,
but:
a. What triggers the valve?
b. Is there any limit to the height of the CLT?
c. Could you have a silo tank in this position?
A. The PMO, Section 7, Item 16p(D), requires that all milk to
milk regenerators be constructed, installed and operated so
that the pasteurized or aseptic product in the regenerator
will be under greater pressure than the raw milk in the
regenerator at all times. We are not aware of any system
or method of accomplishing this other than the use of a
constant level tank, designed and located in such a manner
that the overflow of its top rim is lower than the lowest
milk level in the regenerator. We cannot visualize the use
of valves to accomplish this required pressure differential at
all times.
2.Q. Amount of Product - The Pasteurized Milk Ordinance requires the
"Amount and Name of Pasteurized Milk or Milk Product
Represented by Each Batch or Run on Pasteurized Milk or Milk
Product Represented by Each Batch or Run on the Chart." In the
past, I have not asked for or insisted that the "Amount of Product:
to be on the HTST chart?
A. The PMO Section 7, Item 16p(E), specifies that temperature
recording charts have the "Amounts and name of
pasteurized milk or milk product represented by each batch
or run on the chart." From recent incidents in investigating
food borne outbreaks related to dairy products, the amounts
of product processed has been essential to the investigation.
Should the occasion ever arise when a dairy plant or
regulatory agency be required to produce recording
thermometer charts as evidence, it is essential that the
charts be accurate, legible, and complete with all required
information.
3.Q. Do we have to time the Taylor Magnetic flowmeter in the forward
(above legal cut-in temperature) and diverted (below legal cut-out
temperature positions?
A. Yes. It is necessary to time the Taylor as well as all other
reviewed magnetic flowmeter systems in the legal and sub-
legal temperature positions.
4.Q. Centrifugal Pump - a regulatory agency reported that the
centrifugal pump on the Taylor Magnetic Flow Meter unit does not
stop in any position of the flow diversion valve. This is not so
with the Foxboro units in the state. They indicated that, with the
valve controls in the "inspect" positions, the pump continued to
operate. This condition was also true during the tests required to
shut the metering pump off.
A. There would appear to be some improper wiring in the
"Taylor" system. The Certifugal pump is a flow promoting
device and in accordance with Item 16P, (B), 2, C,(3).
"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
milk is above the required pasteurization temperature as
defined in Definition S of this Ordinance for the milk or
milk product and the process used, or when the diversion
device is in the fully-diverted position."
5.Q. Is there a need for a vacuum breaker downstream from a dual stem
flow diversion valve and upstream from the positive shut-off valve
when a vacuum chamber is downstream from the flow diversion is
in the fully-diverted position."
A. The vacuum breaker upstream from the positive shut off
valve, although preferable, would not be mandatory
providing the leak escape port is open to the floor and not
connected back to the raw milk balance tank. In our
opinion, where the leak escape port is connected to the
balance tank with a sanitary line, the downstream side of
the FDV is not otherwise protected. The least thing that
could happen would be to siphon vapor from the raw milk
balance tank and the most that could happen would be to
siphon raw milk.
6.Q. What requirements must be met in order to operate a homogenizer
(used as a timing pump) during the C.I.P. cycle, with a dual stem
flow diversion device?
A. In order to effectively clean the dual stem flow diversion
devices, it is necessary to "pulse" or move the device from
diverted to forward position several times during the pre
rinse, washing and post rinse cycles. The original review
by MSB and Engineering Branch (EB) specified that the
timing pump could not operate during the CIP cycle.
However, as the popularity of the dual stem device has
increased there has also been an increased interest in using
homogenizers as timing devices on HTST system, it is
necessary to run the homogenizer as timing devices on
HTST systems.
This has caused a slight problem in that, if the homogenizer
is to be cleaned as a part of the HTST system, it is
necessary to run the homogenizer during CLEANED IN
PLACE.
In resolution of this problem, MSB and E.B., have agreed
that the intent of the PMO would be satisfied and the timing
pump (HOMO) could be run during CIP provided the flow
diversion device were kept in the diverted flow positions for
a predetermined time (10 minutes). This would prevent the
inadvertent turning of the switch to CIP and then back to
product run, thereby induction forward flow at sub-legal
temperatures. Wiring diagrams were submitted and
reviewed to provide for these conditions (see copies of the
appropriate M-b memorandums for details of these
changes).
7.Q. Under what condition can a two speed raw product booster pump
be used in an HTST system?
A. A two speed row product booster pump can be operated
during product flow at the low speed and at the high speed
during CIP under the following conditions:
a. The high speed pump must be interlocked with an
automatic CIP system so that once the CIP system is
energized it will continue through its cycle without
interruption until it is completed thereby making it
impossible to go back to product run until the CIP
cycle has been completed.
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