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Far Galaxy
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Posted: Wed Jul 23rd, 2008 01:58 am |
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So I was going to just "know it and move on" kinda deal,
but this question has been driving me crazy in the last couple days that I have to put it up here for some chatting about it.
Q: To prevent backflow in the plumbing line, which would be used?
1. An air gap
2. A surged arrester
3. a spring-loaded check valve
4. A presssure relief valve.
If you choose 1, explain to me what's up with 3 please.
I think 3 is correct, also, don't you think?...urgh.
Thanks
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danielle227
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Posted: Wed Jul 23rd, 2008 02:40 am |
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I want to say that the check valve is the answer because the question is asking for what is used IN the plumbing line.
The air gap isn't in the plumbing line per se, it is the actual space between the rim of the water and the bottom of the faucet.
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Far Galaxy
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Posted: Wed Jul 23rd, 2008 02:47 am |
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thank you. That's exactly how I interpreted, but the crazy thing is 1 is the correct ans. That's why I just couldn't help to throw the ques. on here.
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vaccum
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Posted: Wed Jul 23rd, 2008 12:16 pm |
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http://www.metrowater.co.nz/services/commercial/backflow.aspx
check this link out... very good question!
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Fariba
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Posted: Wed Jul 23rd, 2008 01:02 pm |
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| check valve is the answer, remember that the back flow preventer is another name for the check valve.
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Rkitech78
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Posted: Wed Jul 23rd, 2008 02:45 pm |
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I found this online... this should help...
It seems as though a spring loaded check-valve and an Air gap are both used to prevent backflow in a plumbing line.. however "An air gap is considered the maximum protection available against backpressure backflow or backsiphonage"
here's a link to the website
http://www.treeo.ufl.edu/backflow/faq.aspx
QUESTION: What is a backflow preventer?
ANSWER: A backflow preventer is a means or mechanism to prevent backflow. The basic means of preventing backflow is an air gap, which either eliminates a cross-connection or provides a barrier to backflow. The basic mechanism for preventing backflow is a mechanical backflow preventer, which provides a physical barrier to backflow. The principal types of mechanical backflow preventer are the reduced-pressure principle assembly, the pressure vacuum breaker assembly, and the double check valve assembly. A secondary type of mechanical backflow preventer is the residential dual check valve.
QUESTION: What is an air gap?
ANSWER: An air gap is a vertical, physical separation between the end of a water supply outlet and the flood-level rim of a receiving vessel. This separation must be at least twice the diameter of the water supply outlet and never less than one inch. An air gap is considered the maximum protection available against backpressure backflow or backsiphonage but is not always practical and can easily be bypassed.
QUESTION: What is a residential dual check valve (rdc)?
ANSWER: A rdc is similar to a DC in that it is a mechanical backflow preventer consisting of two independently acting, spring-loaded check valves. However, it usually does not include shutoff valves, mar or may not be equipped with test cocks or ports, and is generally less reliable than a DC. A rdc is effective against backpressure backflow and backsiphonage but should be used to isolate only nonhealth hazards and is intended for use only in water service connections to single-family homes.
QUESTION: What is a double check valve assembly (DC)?
ANSWER: A DC is a mechanical backflow preventer that consists of two independently acting, spring-loaded check valves. It includes shutoff valves at each end of the assembly and is equipped with test cocks. A DC is effective against backpressure backflow and backsiphonage but should be used to isolate only nonhealth hazards.
hope this helps!
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Disgruntled
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Posted: Wed Jul 23rd, 2008 03:07 pm |
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Good question...I would have said check valve.
Excellent answers...I have not heard of an air gap for backflow prior to this.
Far Galaxy, where did you get this question from?
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Far Galaxy
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Posted: Thu Jul 24th, 2008 01:28 am |
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Disgruntled wrote: Good question...I would have said check valve.
Excellent answers...I have not heard of an air gap for backflow prior to this.
Far Galaxy, where did you get this question from?
I pulled it off the freaken "Kaplan" test bank. It's been driving me nuts with that particular question. I should have known better how inaccurate Kaplan is..
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dottie
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Posted: Thu Jul 24th, 2008 07:50 pm |
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| So, air gap was the answer? That was my guess as I watched this thread proceed. That is usually how your house is set up.
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Coach
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Posted: Thu Jul 24th, 2008 09:13 pm |
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danielle227 wrote: I want to say that the check valve is the answer because the question is asking for what is used IN the plumbing line.
The air gap isn't in the plumbing line per se, it is the actual space between the rim of the water and the bottom of the faucet. You're reading too much into it. It says "to prevent backflow in the line" not "what is in the line to prevent backflow."
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alomu
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Posted: Thu Jul 24th, 2008 11:18 pm |
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| Coach: What is it then? Check valve? Air gap?
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Far Galaxy
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Posted: Thu Jul 24th, 2008 11:28 pm |
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Coach wrote: danielle227 wrote: I want to say that the check valve is the answer because the question is asking for what is used IN the plumbing line.
The air gap isn't in the plumbing line per se, it is the actual space between the rim of the water and the bottom of the faucet. You're reading too much into it. It says "to prevent backflow in the line" not "what is in the line to prevent backflow."
You over simplified the question. If it says "to prevent backflow from siphoning", then that is an air gap. The question asks, " backflow in the plumbing line".
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Coach
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Posted: Fri Jul 25th, 2008 12:36 am |
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alomu wrote: Coach: What is it then? Check valve? Air gap? If you're to believe the source above, then it's air gap. The questions sounds like there's some context missing. Obviously, both air gap and check valve could be used.
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Far Galaxy
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Posted: Fri Jul 25th, 2008 12:48 am |
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Coach wrote: alomu wrote: Coach: What is it then? Check valve? Air gap? If you're to believe the source above, then it's air gap. The questions sounds like there's some context missing. Obviously, both air gap and check valve could be used. The question has been duplicated from Kaplan.
There's only one place to put a blame on...eh.
I don't want to duplicate their explanations, because it doesn't help the situation a bit. Basically, the explanation said, you can't use the check valve because it's not allowed. I wish they didn't even print the explanation, because it sounded as odd as the question itself.
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Flyingbuttress
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Posted: Fri Jul 25th, 2008 02:55 pm |
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Far Galaxy wrote: Coach wrote: alomu wrote: Coach: What is it then? Check valve? Air gap? If you're to believe the source above, then it's air gap. The questions sounds like there's some context missing. Obviously, both air gap and check valve could be used. The question has been duplicated from Kaplan.
There's only one place to put a blame on...eh.
I don't want to duplicate their explanations, because it doesn't help the situation a bit. Basically, the explanation said, you can't use the check valve because it's not allowed. I wish they didn't even print the explanation, because it sounded as odd as the question itself.
A friend gave me a copy of the Kraplan test bank when I was studying for MM - my second exam. He swore by it and said I should use it. I was scoring low. I stopped after about 30 questions when I saw some obviously wrong answers...It was messing up what I already knew...Never used it since.
However, what I've learned from this post is that an air gap is acceptable and a check valve is acceptable...I had not heard of the air gap before.
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Coach
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Posted: Fri Jul 25th, 2008 04:42 pm |
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Flyingbuttress wrote: I had not heard of the air gap before. I'll bet you've seen them before. You know that thing that sticks up on a kitchen sink and seems to have no function? That's an air gap for a dishwasher. A lot of people call them bubblers.
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Far Galaxy
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Posted: Fri Jul 25th, 2008 11:38 pm |
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Coach wrote: Flyingbuttress wrote: I had not heard of the air gap before. I'll bet you've seen them before. You know that thing that sticks up on a kitchen sink and seems to have no function? That's an air gap for a dishwasher. A lot of people call them bubblers.
what thing sticks up on the kitchen sink....?
I don't have such thing in my house. Could you show mii a picture pleez.....
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Coach
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Posted: Sat Jul 26th, 2008 06:54 am |
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| Attached Image (viewed 76 times):
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Far Galaxy
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Posted: Sat Jul 26th, 2008 01:52 pm |
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wow, I can't believe I don't have that "thing" sticking out of my kitchen!!never seen one. Thanks for the attachement.
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Rkitech78
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Posted: Sat Jul 26th, 2008 06:01 pm |
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Coach wrote: danielle227 wrote: I want to say that the check valve is the answer because the question is asking for what is used IN the plumbing line.
The air gap isn't in the plumbing line per se, it is the actual space between the rim of the water and the bottom of the faucet. You're reading too much into it. It says "to prevent backflow in the line" not "what is in the line to prevent backflow."
I think the key words in the question are "to prevent"... An air gap would be used to "prevent" backflow.. whereas a check valve would stop back flow. They both work in stoping backflow.. however an airgap would be the best in preventing backflow from occuring in the first place, thus eliminating the need for a check valve.
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Coach
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Posted: Sat Jul 26th, 2008 11:11 pm |
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Rkitech78 wrote: I think the key words in the question are "to prevent"... An air gap would be used to "prevent" backflow.. whereas a check valve would stop back flow. They both work in stoping backflow.. however an airgap would be the best in preventing backflow from occuring in the first place, thus eliminating the need for a check valve. Very good!
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Coach
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Posted: Sat Jul 26th, 2008 11:13 pm |
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Far Galaxy wrote: wow, I can't believe I don't have that "thing" sticking out of my kitchen!!never seen one. Thanks for the attachement. I don't have one either but grew up with one. I believe the garbage disposal works as an air gap these days.
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