Anti-vac valve
This valve is used to minimise the risk of tanks imploding. This is used for tanks which are exposed to vacuum, this can occur during emptying, cool rinsing after hot-cleaning or caustic cleaning in a carbon dioxide atmosphere. The anti-vac valve is to be placed on any closed tank.
The way in which physics is used in this piece of equipment is that if the pressure inside the tanks gets too low then the CWM which is caused by the difference in pressures, the outside pressure being higher then the inside one, will become greater then the ACWM which is the moment of the counter weight. This then involves the valve opening so that the two pressures equal out with each other, therefore it changes the low pressure inside to get to higher pressure which equals the pressure of the air outside to prevent the tank imploding.
This valve is used on any closed tank.
Calculations for the anti-vac valve.
From the diagram before I know 4 pieces of information to find out what the two moments need to be.
Firstly for the ACWM (anti-clockwise movement) I know that counter weight is 5kg, the gravity is 9.81 N, the distance from the pivot is 0.3m and for the CWM (clockwise movement) moment I know that the distance from the pivot is 0.1m.
If the ACWM 5kg x 9.81N x 0.3m which is equal to 14.715Nm, from this I know that the CWM needs to equal 14.715Nm.
So to find the CWM I divide the 14.715 by 0.1 I get 147.15N. This is the value that the pressure needs to be coming from outside of the tank to balance these two forces.
Pressure relief valve
The pressure relief valve is used to help prevent the risk of the tanks getting damaged from causes such as over pressurising or liquid overfill.
The way in which physics is used in this valve is that if the pressure from the carbon dioxide inside the tank is too great then the valve opens to release that pressure so that it doesn’t cause any damage to the tank. For this to happen then the ACWM, which is the carbon dioxide, needs to be greater than the CWM, which is the counter weight moment, this would then allow some of the pressure to escape and return the pressure inside the tank to normal so that the can go back to normal and close.
Calculations for the anti-pressure valve.
From the diagram before I know 4 pieces of information to find out what the two moments need to be.
Firstly for the CWM I know that counter weight is 5kg, the gravity is 9.81 N, the distance from the pivot is 0.4m and for the ACWM moment I know that the distance from the pivot is 0.15m.
If the CWM is 5kg x 9.81N x 0.4m which equals 19.62Nm then the ACWM needs to equal 19.62Nm.
I know the distance from the pivot is 0.15m, so if I divide 19.62Nm by the 0.15m I will get the value for which the pressure of the carbon dioxide is coming out of the fermenting vessel, which is 130.8N.
There are several limitations for these two valves which are; they might not be as sensitive as they could be, not able to detect small changes in pressure. Also they are self running it could taken longer for it to get fixed if it breaks rather than if it relied on a human operating it, so in that the fact that it was broken would get fixed quicker. The equipment is expensive as there is lots of metal
On the other hand there are many different advantages for these valves, which are; the position of the counterweight can be easily adjusted to compensate with different amounts of pressure from within the tank or from outside. Also the design of the mechanism is of a very simple one, this is an advantage because it is vary easy to understand and therefore it is less likely for a human to break it. The mechanism is also not likely to break again because it is a simple deign which means that there are fewer things which can go wrong. The mechanisms can also self-reset, this means that it can close itself and repeat the operation over and over again without human intervention, this is an advantage because it can run itself without any need for human intervention. The mechanism has low-cost maintenance, this means that the two valves need little human activity to kept these mechanisms running and that it won’t cost much to kept them running.
To develop this equipment further you could control it via computer. This would ensure accurate changes it the valves to adjust to the different conditions facing them more easily.
The pressure relief valve could be used for hot water systems, gases and non-corrosive fluids. The anti-vac valve can be used in hot water heaters.
http://www.plumbworld.co.uk/3-bar-relief-valve-12-3-bar-231-60
http://www.rwc.co.uk/Public/gplumb/antivac.pdf
http://www.scandibrew.co.uk/pressure_releif_valve.htm
http://www.scandibrew.co.uk/anti_vacuum_valve_dead_weight_type.htm