VACUUM REGULATION IN A MILKING SYSTEM (CMFBMP DAIRY
GUIDELINES) .
Proper sizing, installation and maintenance of the VACUUM
REGULATOR can have a CRITICAL IMPACT on both milk production and
udder health.
The primary function of the vacuum regulator is to maintain a
stable vacuum at a preset level in the milking system. It
accomplishes this by varying the amount of air admitted through its
air admission opening in response to changing air admissions into
the milking system (i.e. attaching and detaching units.)
Vacuum Level Settings For Different Milking Systems
| System Description |
Desired Range in System Vacuum |
| 1. Lowline (direct from claw to milkline) |
12.5 to 13.5 in.Hg |
| 2. Centre mount weigh jar systems |
13.5 to 14.5 in.Hg |
| 3. Highline (with no automation) |
14.0 to 15.0 in.Hg |
* The precise setting of system vacuum should be based on
measuring the teat end vacuum levels at milking time of a
cross-section of eight(8) to 10 cows during the peak milk flow
period of each cow. The desired teat end vacuum level during peak
milk flow is in the range of 10.5 to 12.0 in.Hg. However, to achieve
this, the system vacuum level must be set within the vacuum ranges
listed above according to the type of milking system that exists.
** The inclusion of various pieces of automation in the milking
system (i.e. milk meters, automatic takeoffs, etc.) may also have an
impact on the precise setting of system vacuum. These must be taken
into account when establishing the desired system vacuum level.
Vacuum regulators vary in terms of cost, design, style,
sensitivity to system vacuum changes and airflow capacity ratings.
Performance variations among vacuum regulators are or can be due to
differences in regulator design, regulator capacity relative to
vacuum pump capacity, sizing and plumbing of vacuum lines, location
of the regulator in the system and level of maintenance.
Common types of vacuum regulators include weighted, weighted oil
bath, coil spring and servo- diaphragm. Various makes of the more
desirable servo-diaphragm regulators exist. They are highly
recommended because of their increased sensitivity and ability to
control and maintain system vacuum compared to the older styles.
Vacuum regulator capacity is commonly expressed in both Cubic
Feet per Minute (or CFM) and Litres per Minute (or L/min) at 15.0
inches of mercury (in.Hg.) vacuum under the American Society of
Mechanical Engineers (ASME) Standard.
Vacuum Regulators Commonly Found on Manitoba Dairies
| Regulator Type |
Company |
Brand Name* |
Personal Rating** |
Recommended vs Not Recommended |
| A. Servo-diaphrgm |
Alpha Laval |
VR |
Exellent |
Recommended |
| Boumatic |
Vou-Vac |
Excellent |
Recommended |
| NuPulse |
Vacumaster |
Excellent |
Recommended |
| Surge |
Commander |
Excellent |
Recommended |
| West Dairy Res |
Sentinel |
Excellent |
Recommended |
| Westphalia |
Vacurex |
Excellent |
Recommended |
| B. Coil Spring Tension |
Surge |
Equalizer |
Poor to Fair |
Not Recommended |
| Weighted Oil Bath |
Surge |
Filtered-Air |
Poor to Fair |
Not Recommended |
| Weighted Oil Bath |
Surge |
High Capacity |
Poor to Fair |
Not Recommended |
| Weighted |
Universal |
Vacuum Controller |
Poor to Fair |
Not Recommended |
| Weighted |
Alpha Laval |
Junior Controller |
Poor to Fair |
Not Recommended |
| Weighted |
Alpha Laval |
Senior Controller |
Poor to Fair |
Not Recommended |
| Weighted |
Generic Makes |
Vacuum Controller |
Poor to Fair |
Not Recommended |
* Many of these vacuum regulators are available in different
sized capacities. Proper regulator capacity selection relative to
vacuum pump capacity is CRITICAL in achieving desired system vacuum
regulation.
** Any vacuum regulator will perform poorly if not properly
installed, if system plumbing is inadequate, if regulator capacity
is undersized, or if the regulator is not properly maintained (i.e.
cleaned, filters changed, etc.). My "personal rating" of each
regulator is based on field experience in testing the ability of
each regulator to pass the "industry standard vacuum regulator
performance test" under the conditions that system design and
regulator maintenance are not a problem.
With respect to selecting a vacuum regulator of sufficient air
flow capacity, the general rule of thumb is that the regulator
selected and installed should supply at least 125% of full vacuum
pump capacity at a system operating vacuum of 15.0 in.Hg.
In addition, proper location of the vacuum regulator can have a
critical impact on its performance. The regulator should be
installed on the main vacuum supply line preferably as close to the
sanitary trap as possible but not directly over the wash sink.
Vacuum pump capacity is not related to vacuum regulator
performance. Increasing vacuum pump capacity cannot compensate for
poor regulator function. Likewise, a sensitive regulator cannot
compensate for a lack of pump capacity.
During the past eight(8) years I've performance tested 232 vacuum
regulators in Manitoba. Of these, I've detected 75% with performance
problems serious enough to adversely affect production and/or udder
health.
Further improvements in system vacuum regulation can be expected
in the near future with the introduction of new, improved vacuum
regulation designs known as Variable Frequency Drive (VFD) Vacuum
Pumps and Proportional-Integral-Derivative (PID) Control Units.
Article written by:
Tom Droppo, B.Sc.(Agr.),M.Sc.,P.Ag.,C.I.M. Manitoba Dairy
Specialist Animal Industry Branch, Manitoba Agriculture Telephone:
(204) 945-7670 Fax: (204) 945-4327
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