Search results
Search results 1-11 of 11.
[corrected an error in previous posting] After studying the Wilkins valve I have now understood the following. Essentially the pressure vacuum breaker PVB consists of two separate valves in one. The first valve is similar to what is found in an atmospheric vacuum breaker (AVB) with one exception -- the poppet which adds some weight to encourage the atmospheric valve contained in both PVBs and AVBs to open. Both the atmospheric vacuum breaker and the pressure vacuum breaker have a seal to atmosph...
After studying the Wilkins valve I have now understood the following. Essentially the pressure vacuum breaker PVB consists of two separate valves in one. The first valve is similar to what is found in an atmospheric vacuum breaker (AVB) with one exception -- the poppet which adds some weight to encourage the atmospheric valve contained in both PVBs and AVBs to open. Both the atmospheric vacuum breaker and the pressure vacuum breaker have a seal to atmosphere (the "atmospheric valve" I call it) w...
Another web based resource from the folks at the University of Southern California http://www.usc.edu/dept/fccchr/intro.html Trying to understand the functioning of the Pressure Vacuum Breaker... seems a bit subtle. Will post when I find a better explanation. The main problem for the residential sprinkler irrigation system seems to be backsiphonage which can open up the solenoid valves when the system is open to the potable water supply for months during the growing season. The atmospheric vacuu...
Picked up a Wilkins Model 720A Pressure Vacuum Breaker today for a bit over $60 including tax (non-ferrous metal construction -- brass or bronze -- as you suggest). []
Hi Wetboots, Regarding your comment about township inspectors not standing behind the homeowner after passing an inspection... I'm thinking that the importance of the inspectors comes in after any loss occurs and the homeowners' insurance company might seek to escape payment by claiming that the homeowner did not properly obtain inspections. If the town were to pass inspection on the AVB and someone were harmed, presumably the insurance policy would have to pay. The same might not be the case ot...
More on backflow resources on the web: 1. The American Backflow Prevention Organization http://www.abpa.org/ 2. CASE HISTORIES OF SELECTED BACKFLOW INCIDENTS FLORIDA DEPARTMENT OF ENVIRONMENTAL PROTECTION http://www.mindspring.com/~loben/casehist.htm http://www.treeo.ufl.edu/backflow/casehist.asp#25 3. Backflow Prevention Techzone http://www.backflowpreventiontechzone.com/ What is very hard to find, however, is specific information on the problems associated with backflow. Clearly, the one case ...
I'm doing a little prospecting on the WWW to find support for your strong statements about backflow. from http://www.treeo.ufl.edu/backflow/casehist.asp#25 25. - BACKFLOW AT A PREMISES WHERE THE CONSUMER'S POTABLE WATER SYSTEM SUPPLIES AN IRRIGATION PIPING SYSTEM DATE OF BACKFLOW INCIDENT: October 1991 LOCATION OF BACKFLOW INCIDENT: Southgate, Michigan SOURCE(S) OF INFORMATION: - Drinking Water & Backflow Prevention, Volume 9 Number 6 (June 1992) - Pacific Northwest Section of the American Water...
Hi "Wetboots" This does seem to have turned into the proverbial can of worms. As for the solenoid not providing any protection against backflow, I do believe that depends on their being some signficant positive pressure and water supply (both factors) in the irrigation lines in excess of that in the potable water system. I mean, I don't think the solenoid is a wide open sluice gate for backflow. However I suspect you are correct that they are designed to hold off a head of pressure coming from t...
Wetboots, Thanks for your reply. You clued me in to the correct nomenclature of AVB and PVB. A quick web search revealed helpful information I was not able to find without that nomenclature. I received the Irritrol part and was able to install it. {711 Series 3/4" Cap & Float (BPHR-7) } As a result, my irrigation system now functions as historically it did, but (as you ably point out) using an AVB upstream of the solenoid valves causes this AVB to remains under pressure and will not protect the ...
Responding to your comment, Wet Boots, I would doubt the previous homeowner would have skimped, but I have little doubt that his installer might have cut corners and put a few $$$ away thereby for his son or daughter's college savings. [] Actually this device is at least 1.5 feet higher than any emitter, so the PVB should work. Is this an "anti-siphon valve" and if not what's the difference? I'm assuming that the issue with backflow is that water in the sprinkler system can enter the home under ...
Hi! My sprinkler system is leaking from (what I assume is) the backflow valve where the pipe emerges from the foundation about a foot off the ground. [:I] I removed the two-inch (or so) diameter hex cap which is green and says "Richdel 3/4" valve 150 psi max 110ºF H2O max 'R705' Carson City, Nevada" on it. The cap has a kind of bonnet on it through which water can escape when it's closed (see below). This cap has a small white plunger inside which I gather is some kind of shut off device which o...
