Hope i explain it ok ,,if not call me ,lol

Quote: Originally Posted by jhale I have two ball valves on my skimmer, one going in, and one coming out. for the DAS they work well enough.

you have an extrenal DAS right

[TimberTDI]

http://www.cheresources.com/valvezz.shtml

Gate Valves

Best Suited Control: Quick Opening
Recommended Uses:
1. Fully open/closed, non-throttling
2. Infrequent operation
3. Minimal fluid trapping in line

Applications: Oil, gas, air, slurries, heavy liquids, steam, noncondensing gases, and corrosive liquids
Advantages: Disadvantages:
1. High capacity 1. Poor control
2. Tight shutoff 2. Cavitate at low pressure drops
3. Low cost 3. Cannot be used for throttling
4. Little resistance to flow

Globe Valves
Best Suited Control: Linear and Equal percentage
Recommended Uses:
1. Throttling service/flow regulation
2. Frequent operation
Applications: Liquids, vapors, gases, corrosive substances, slurries
Advantages: Disadvantages:
1. Efficient throttling 1. High pressure drop
2. Accurate flow control 2. More expensive than other valves
3. Available in multiple ports


Ball Valves
Best Suited Control: Quick opening, linear


Recommended Uses:
1. Fully open/closed, limited-throttling
2. Higher temperature fluids

Applications: Most liquids, high temperatures, slurries


Advantages: Disadvantages:
1. Low cost 1. Poor throttling characteristics
2. High capacity 2. Prone to cavitation
3. Low leakage and maint.
4. Tight sealing with low torque
Butterfly Valves
Best Suited Control: Linear, Equal percentage
Recommended Uses:
1. Fully open/closed or throttling services
2. Frequent operation
3. Minimal fluid trapping in line
Applications: Liquids, gases, slurries, liquids with suspended solids
Advantages: Disadvantages:
1. Low cost and maint. 1. High torque required for control
2. High capacity 2. Prone to cavitation at lower flows
3. Good flow control
4. Low pressure drop

[Deanos]

Quote: Originally Posted by TimberTDI http://www.cheresources.com/valvezz.shtml

Thanks! I read your link, but it doesn't seem to apply to PVC valves?

[Tonyscoots84]

[TimberTDI]

This is from plumbingsupply.com


"I can't find a listing for PVC gate valves. Do you offer them as well?"
Because our goal is for 99% customer satisfaction we do not wish to sell PVC gate valves. They are not as reliable as PVC ball valves and they tend to break easily due to their shaft being plastic as well. If you "insist" on (or must have) a gate valve then we highly recommend purchasing a top quality brass gate valve (which we do offer and do recommend).

[Tonyscoots84]

we use em for our tanks not a or submarine. most gate valves dont get touched to much because of there in tune dialing.. i have my gate valve on a skimmer and its been great and reliable.. it all depends on what the intentions are for... but for fine tuning a skimmer i prefer a gate valve....

i think ronen said it well if your looking for an on and off kind of thing then ball valve is the way to go but u can do the fine tuning like a gate valve...

ohh yea brass is a no no with saltwater...

[Deanos]

Quote: Originally Posted by TimberTDI This is from plumbingsupply.com "I can't find a listing for PVC gate valves. Do you offer them as well?" Because our goal is for 99% customer satisfaction we do not wish to sell PVC gate valves. They are not as reliable as PVC ball valves and they tend to break easily due to their shaft being plastic as well. If you "insist" on (or must have) a gate valve then we highly recommend purchasing a top quality brass gate valve (which we do offer and do recommend).

LOL..I read that. We weren't discussing reliability, but flow control. If you want to put a brass gate valve on your tank, go ahead, but I don't think that's a good idea.

[simike]

Can ball valves create any noise or air bubbles when partially closed.
It seems like gate valves should be used when you have a senesitive skimmer, and ball valves can be used at any other time

[Deanos]

Quote: Originally Posted by simike It seems like gate valves should be used when you have a senesitive skimmer, and ball valves can be used at any other time

Exactly! I wouldn't use a gate valve on a return pump line. The control a ball valve gives, will suffice in this situation.