Re: Waking Sleeping Beauty
Posted by HH56 On 2012/5/27 15:08:04
Hope you get to feeling 100% soon.
MPB says a minimum of 400 psi is needed to slow and stop an average car. I know that in the process of doing my little exercise, 400 doesn't cut in on a Packard -- slows, yes. Stop in a panic -- dream on. 400 barely keeps it still when putting it in gear. As mentioned, I measured 800psi with 100 on the pedal with the BTV using 21 inches of vacuum from an external source. My Packard actually has a bit less vacuum so pressure would be somewhat less.
Considering you are usually not going to stand on the pedal, then I think 600 is reasonable for an average controlled stop. Of course, if the compensating valve goes out, you will be standing, pulling, swearing and maybe soiling the upholstery so who knows for sure how much will be present then. Since pressure couldn't vent or get back to the reservoir thru the backflow valve, then all will be felt. The BTV having the ram displacement to move fluid instead of a piston kind of messes up the ordinary comparison calculations.
Several places have brass or steel check valves which will contain the pressure. Problem I see with those is they pretty much all take a minimum of 2psi to open the valve. Would wonder if fluid could pass into the reservoir at all with that minimum. McMaster has a fairly decent assortment if the backflow preventer you have or your friend isn't able to improve needs to change.
Here are a couple of photos. First is off the MPB website with their statement of pressures. Second is of BTV pressures I documented when first contemplating my still ongoing project.
Attach file:
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MPB says a minimum of 400 psi is needed to slow and stop an average car. I know that in the process of doing my little exercise, 400 doesn't cut in on a Packard -- slows, yes. Stop in a panic -- dream on. 400 barely keeps it still when putting it in gear. As mentioned, I measured 800psi with 100 on the pedal with the BTV using 21 inches of vacuum from an external source. My Packard actually has a bit less vacuum so pressure would be somewhat less.
Considering you are usually not going to stand on the pedal, then I think 600 is reasonable for an average controlled stop. Of course, if the compensating valve goes out, you will be standing, pulling, swearing and maybe soiling the upholstery so who knows for sure how much will be present then. Since pressure couldn't vent or get back to the reservoir thru the backflow valve, then all will be felt. The BTV having the ram displacement to move fluid instead of a piston kind of messes up the ordinary comparison calculations.
Several places have brass or steel check valves which will contain the pressure. Problem I see with those is they pretty much all take a minimum of 2psi to open the valve. Would wonder if fluid could pass into the reservoir at all with that minimum. McMaster has a fairly decent assortment if the backflow preventer you have or your friend isn't able to improve needs to change.
Here are a couple of photos. First is off the MPB website with their statement of pressures. Second is of BTV pressures I documented when first contemplating my still ongoing project.
Attach file:
(14.86 KB)
(71.22 KB)
(66.26 KB)
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