Harbor Freight Pump
Posted 19 April 2012 - 01:14 PM
Posted 20 April 2012 - 05:20 AM
This protocol has been developed for use with the oil-based rotary-vane vacuum pumps typical of those manufactured by US General and sold by Harbor Freight when degassing wine under vacuum.
These types of rotary-vane vacuum pumps use petroleum based, high vacuum oil in their sumps and rotor cartridges for the purpose of sealing, lubrication and cooling. When used in HVAC applications, the hydroscopic oil is used to absorb and remove moisture from the vacuum pump.
It has been established that these inexpensive, high-performing 75 micron and 25 micron vacuum pumps are not protected by any check-valve in the suction manifold that would prevent oil vapour and oil from being sucked out of the pump and backwards into the wine being degassed under vacuum.
The purpose of this protocol is to minimize the risk of the wine being contaminated by oil.
This protocol is primarily intended for use when vacuum degassing wine but it may be similarly applied to the vacuum transfer and to the vacuum racking of wine.
It is common practice for the suction tube from the vacuum pump to be connected to the partially full wine carboy through an intermediate overflow canister.
It is common practice for the suction tube coming from the over-flow canister to be connected to the carboy by means of a drilled rubber-bung.
It is the intent of this Purging Protocol to modify these common plumbing practices, in order to provide for continuous system purging, as follows:
1) The suction tube entering the drilled rubber-bung in the wine carboy must be cut just downstream of the rubber-bung and fitted with a tee-piece.
2) The protruding leg of the tee-piece must be fitted with an adjustable shut-off ball or needle valve that can draw in air from the atmosphere. Call this adjustable valve the purging valve.
3) The suction tube continues from the tee-piece back to the overflow canister but must be fitted with a shut-off valve of any type. Call this shut-off valve the emergency shut-off valve.
4) The plumbing in the interior of the overflow canister and that which continues to the suction manifold on the vacuum pump remains as before.
It has been established that, when the entire system is in vacuum equilibrium throughout, it is possible for oil vapour that arises in the vacuum pump to migrate backwards through the unprotected suction manifold into the plumbing, through the overflow canister and into the wine in the carboy.
This situation will typically arise when the vacuum pump is turned off and the carboy is still hooked up to it. The residual vacuum in the carboy will draw air, in through the vacuum pump picking up the oil contaminants in it, backwards into itself.
The intent of the Procedures described in this Protocol is to ensure that whenever the carboy is hooked up to the vacuum pump there will always be a purging gas-flow from the carboy towards the vacuum pump. In the context of this Protocol, gas means air, carbon dioxide or oil vapour.
The intent is to prevent any situation arising at any time in which there is:
a) No purging downstream gas-flow in the system
A contaminating upstream gas-flow from the vacuum pump towards the carboy.
1) Hook up the entire system but do not insert the rubber-bung into the carboy.
2) Ensure that purging valve is fully open.
3) Ensure that the emergency shut-off valve is fully open.
4) Start the vacuum pump. You will hear the hiss of air as it is sucked in through the open purging valve and through the open end of the suction tube passing through the rubber-bung.
5) Allow the vacuum pump to freely suck in and draw air through the plumbing and through the overflow canister for at least 15 seconds to ensure that the system is purged of any oil contaminants.
6) Insert the rubber-bung into the mouth of the carboy. You will hear the hiss of air as it continues to be sucked in through the open purging valve.
7) Slowly close the purging valve until an increasing vacuum is pulled in the headspace of the carboy.
The purging valve can be used to adjust the vacuum so that the desired amount of degassing bubble activity is evident. To increase the vacuum in the headspace, close the purging valve some more. To reduce the vacuum in the headspace, open the purging valve some more.
To ensure that the purging gas-flow in the system is always in the direction of carboy towards vacuum pump and that the system is always being purged of oil contaminants, never close the purging valve fully.
This applies most definitely to the unlikely event in which there appears to be no more carbon dioxide bubbling out of the wine.
A purging valve that is always partially open will ensure that the vacuum in the carboy is always less than the vacuum in the overflow canister and in the vacuum pump itself. The gas will flow from lowest vacuum to highest vacuum. This will ensure that the gas-flow is always from the carboy (low vacuum) towards the overflow canister (medium vacuum) and then towards the vacuum pump (highest vacuum).
IMPORTANT NOTE: Do not turn off the vacuum pump until very last.
1) Open the purging valve fully to relieve as much of the vacuum in the carboy as possible. You will hear the hiss of the air as it is sucked in through the open purging valve. Allow the vacuum pump to draw in the air for at least 15 seconds to purge the system of oil vapours if any.
2) Pry the rubber-bung loose and remove it from the carboy. You will again hear the hiss of air as it is sucked in through the open purging valve and through the open end of the suction tube passing through the rubber-bung.
3) Seal the carboy with an appropriate stopper.
4) Turn the vacuum pump off.
If during the vacuum degassing operation you observe oil vapour condensing anywhere in the system or oil beginning to emerge from the suction manifold on the pump:
1) Immediately close the emergency shut-off valve between the overflow canister and the carboy.
2) Open the purging valve fully and wait until the vacuum in the carboy is completely relieved.
3) Pry the rubber-bung loose and remove it from the carboy.
4) Immediately seal the carboy with an appropriate stopper.
5) Open the emergency shut-off valve between the overflow canister and the rubber-bung. This will allow the free flow of air into the system and enable the vacuum pump to draw the oil vapour and oil back into itself. Allow sufficient time to recover as much of the oil contaminants as possible.
6) Turn the vacuum pump off.
1) Wash all oil contaminated equipment with a suitable detergent, rinse and dry.
Posted 20 April 2012 - 10:02 AM
Posted 20 April 2012 - 10:54 AM
0 user(s) are reading this topic
0 members, 0 guests, 0 anonymous users