1/2" vs 3/4"

[wuertele]

I am seeing a lot of brewing equipment based on 1/2" i.d. ports, and I've never seen 3/4". It seems like there is a de-facto standardization on 1/2".

I happen to have access to some 3/4" SS fittings and valves that I think might make an awesome brewery. I could find a 3/4" pump and reconfigure my pots for 3/4". Other than cost, is there any reason why 1/2" is better than 3/4"?

 

[jvino]

I was wondering the exact same thing. I'm actively searching for kegs to convert and was considering 3/4" as well. Drawbacks?? Also, what is the best source for SS couplers to be welded in. Is there a diagram of the typical placement?? Thinking BCS controlled HERMS for my rig.

 

[shushikiary]

IMO, but remember it's just an opinion..

1. Cost. 3/4 stainless fittings can get stupid expensive.

2. Getting 3/4 fittings to seal (weldless) is harder in my experience than 1/2 due to the added curvature of the pot/keg at that diameter hole.

 

[Catt22]

IMO, also just an opinion, nothing more:

The typical 1/2" fittings are more than adequate for the typical homebrew setup with kettles in the 5-20 gal range and probably even larger than that. The biggest resistance to the flow rate is usually the tubing, piping and connectors used. I have seen a lot of systems that use 1/2" hoses, but the ID of the connectors is frequently much smaller. Barbed fittings for 1/2 ID tubing are only about 3/8" ID. Then I see a lot of herms coils and cfc coils made of 1/2" OD tubing, but again, the ID is only 3/8" or so. I use 5/8" ID hoses (7/8" OD) throughout my system with the intent to have nothing less than 1/2" ID anywhere including the ID of the connectors. There is also a limit to how fast you can circulate a HERMS or RIMS due to the false bottom or manifold design. With most, you can's circulate at a rate much faster than gravity alone would provide or you wind up with a stuck mash. So, what I'm trying to say is that there isn't a big advantage to be gained using 3/4" fittings even if you use larger hoses and tubing. I don't see any problems with using the 3/4" fittings and you can always bush them down if desired, but buying a few SS fittings isn't a major expense anyway so I would just go with the 1/2" if it were me making the decision.

 

[bf514921]

agree with the 1/2, however for my mashtunn i am upgrading to 3/4 figure it will help with flow and stuck sparge, upgrading from copper to all stainless. allso +1 on rigs with 1/2 in everthing but 3/8 hose and barbs.

 

[Catt22]

agree with the 1/2, however for my mashtunn i am upgrading to 3/4 figure it will help with flow and stuck sparge, upgrading from copper to all stainless. allso +1 on rigs with 1/2 in everthing but 3/8 hose and barbs.

Upgrading to 3/4" fittings likely won't help to avoid stuck sparges. It's been my experience that anytime you exceed about 1-1/2 - 2 psi of suction on a false bottom it will usually result in a compacted grain bed at some point. There are number of variables involved that can lead to a stuck sparge/recirc, but the number one cause is applying too much suction to the FB. Trying to pump with more force only makes it worse. I'm running a direct fired RIMS and a high flow rate works best, but if I exceed the speed limit of the FB it will get stuck every time. The only time I can run wide open with everything is while chilling the wort. I do the recirculation loop through a CFC and back into the BK for the whirlpool effect. At that point, the FB is out of the circuit and no longer inhibiting the flow rate. Only then can I take full advantage of the larger hoses and fittings.

 

[beerthirty]

Cat is pretty much on target here. The common pump used is 1/2" ID which is adequate for our application provided you don't have a serious lift issue. By matching the pump ID to the hose and connector ID you will be assured of flow rates posted by the pump manufacturer for the design and build of your system. Now for example you have a 1/2 pump and have plumbed in 1" It might seem that you would be able to max out your flow rates but in a lift you would actually reduce them by a factor of 4. The weight of the material lifted would cause a 400% reduction in flow at the rated height. Wish I could explain the mechanics of it. I have done the math back in school and it is simple physics, which is no longer simple to me. The biggest issue is to make sure that the diameter of the fluid flow remains the same as the pumps ID. Larger tubing then the pumps ID and you have reduced pressure and possibly flow depending on lift. Smaller than the the pump ID and you have increased pressure but have not increased flow due to the restriction in the tubing. OK my brain hurts, hope someone else was more helpful.

 

[Catt22]

Clipped from above: "Now for example you have a 1/2 pump and have plumbed in 1" It might seem that you would be able to max out your flow rates but in a lift you would actually reduce them by a factor of 4. The weight of the material lifted would cause a 400% reduction in flow at the rated height."

This isn't correct. While a 1" ID does have four times the cross sectional area of the 1/2" ID hose, the static pressure head would be the same for each. It's only a function of the lift height and in a dynamic situation the total head would be a function of the lift height plus the frictional losses in the hose and fittings. You would have less resistance with the larger hoses and fittings, so for a given lift height they would increase the flow rate, not reduce it. The pressure at the bottom of a static column of water (or whatever) for a given height (or depth) is the same regardless of the cross sectional area of the column. IMO, this is a good thing.

 

[beerthirty]

Ok Catt, I got a little twisted up in thought and didn't get across what I was trying to say correctly. I was dealing with the total lift of the pump. IIRC a march has 12.1 feet. By trying to push 4 times the volume of water it would reduce the lift to about 3 ft. If the the wight of fluid at the bottom of the lift is increased by a larger diameter tube, so is the pressure. Since lift height is a factor of pressure at the bottom of the lift and the pressure has increased, then the lift height is reduced by the same factor. Not many rigs out there can claim less than 3 feet in height.

 

[Catt22]

Ok Catt, I got a little twisted up in thought and didn't get across what I was trying to say correctly. I was dealing with the total lift of the pump. IIRC a march has 12.1 feet. By trying to push 4 times the volume of water it would reduce the lift to about 3 ft. If the the wight of fluid at the bottom of the lift is increased by a larger diameter tube, so is the pressure. Since lift height is a factor of pressure at the bottom of the lift and the pressure has increased, then the lift height is reduced by the same factor. Not many rigs out there can claim less than 3 feet in height.

Nope, this still isn't correct. The head would be the same regardless of the hose diameter. The static pressure at the bottom of a 12.1 ft hose would be 5.24 psi whether the hose is 1 inch or 6 inches in diameter. The pump would not be trying to pump 4 times the volume of water with a 1 inch hose vs. a 1/2 inch hose and the maximum lift or head would not be reduced. The pump would max out at 12.1 ft with either hose and the flow rate at that head would be near zero for either. Take a look at this pump curve for the 809 and notice that the flow rates are a function of the pressure head only:

http://www.marchpump.com/documents/curves/Hydronic_Pump-Series/809-PL-HS.pdf

Obviously, for a dynamic flow you would need to consider the frictional losses in the hoses and fittings in order to calculate the actual flow rates, but otherwise the pressure is a function of the head (or lift if you prefer). The water pressure is the same at the bottom of your ten foot deep swimming pool as it is in a ten foot deep lake. I think you are confusing total weight with unit force (pressure). They are not the same thing.

 

[GreenMonti]

Nope, this still isn't correct. The head would be the same regardless of the hose diameter. The static pressure at the bottom of a 12.1 ft hose would be 5.24 psi whether the hose is 1 inch or 6 inches in diameter. The pump would not be trying to pump 4 times the volume of water with a 1 inch hose vs. a 1/2 inch hose and the maximum lift or head would not be reduced. The pump would max out at 12.1 ft with either hose and the flow rate at that head would be near zero for either. Take a look at this pump curve for the 809 and notice that the flow rates are a function of the pressure head only:

http://www.marchpump.com/documents/curves/Hydronic_Pump-Series/809-PL-HS.pdf

Obviously, for a dynamic flow you would need to consider the frictional losses in the hoses and fittings in order to calculate the actual flow rates, but otherwise the pressure is a function of the head (or lift if you prefer). The water pressure is the same at the bottom of your ten foot deep swimming pool as it is in a ten foot deep lake. I think you are confusing total weight with unit force (pressure). They are not the same thing.

+1

Catt is right. 10' (or whatever depth/height) is the same pressure for any number of gallons. If a 100 gallon tank is 18" deep and a 10 gallon tank is 18" deep, there is no more pressure at the bottom of the 100 gallon tank then the 10. Plumbing can be larger then the pumps intake or output, but smaller is bad.

As others have mentioned. Larger fittings will just cost you more. If cost isn't a concern. Then use them. They will look burly. You'll have a fatty look to your system. If you match your pump to your fittings, you will just be using more energy then necessary. Your gonna need to throttle it down a lot. You just don't need much flow in home brewing. Now, this thought is based on 5-10ish gallon batches. How big do you want to run?

I like the idea of the larger fitting on a mash tun drain. Not for more flow, but for better velocity at the opening. It will slow things down. It will also help the flow vectors going into the drain. I plan to weld on a reduction fitting in the bottom of my MLT. A 2" to 1/2" pipe weld fitting. It is about 3" long.

Edit; IIRC a 1/2" drain with no pump in a full siphon running down 4 feet, will do something like 300-400 GPH.