Posted Thu May 17, 2012, 2:14pm Subject: Re: Pressure Profiling via 3-way directional solenoid valve
hahah if im gonna tear into the machine and replaces valves and add tubing etc, i think i'll just spend the extra few bucks for the solenoid. hahah imagining manually turning a valve(and installing a cheapie manual valve and likely having upgraditis and wanting a solenoid later) is kinda silly to me.
btw, regarding the tubing from the pump to the boiler(and all the tubing im gonna have to get), is silicon gonna be good enough to hold the pressure and deal with the bit of heat that the boiler is gonna put out(the tubing will be before the boiler but imagine the connection will heat up).
i'm looking into teflon tubing now. i really shouldnt need more than about a foot of it anyways. i noticed that espressoparts.com sells a regular silicon tube for the type of connection i need but then i see places like partsguru selling teflon tubing. i'll probably be safer with teflon...bleh. more money. maybe i should just go with a manual switch afterall hahah. nooo! :P
oh and regarding the pressure reading from the steam wand, im hoping it will be somewhat accurate. the plan is to put a puck of coffee into the portafilter or maybe find a blind basket that will fit and measure the pressure at the steam wand with it completely open. another option maybe is to connect a T before the boiler and after the shuttle valve and hook it up directly to a pressure gauge. It might get pretty tight in the casing.
But then this will measure before the boiler and it wont give me brewhead pressure, right?
Maybe the portafilter mounted pressure gauge may be the best bet(although, in my head, i feel like i'd be getting the same pressure by measuring the steam wand). Problem with this is added cost as i'd need to get the spouted unpressurized portafilter for about another 60 bucks then another gauge for 10+ bucks. bah...your manual valve idea is getting more tempting now. hahaha
as far as heat, silicon brand, silicone and teflon(ptfe) tubing shouldnt have any problem with the temperatures that we are dealing with. i believe the standard silicone stuff can withstand 350F and the silicon stuff can do 500F. Teflon also can be used at a continuous 500F temperature.
the issue then comes to pressure. Silicon and most silicone tubing will burst at a fairly low pressure that would not work for our espresso pump pressures. Reinforced silicone will however be ideal. The Silbrade Reinforced silicone tubing with a 1/8" ID has a working pressure of 233psi(about 16bar) and a burst PSI of 699. Teflon will burst at about 965psi in the 1/8" ID.
D4F Senior Member Joined: 15 Mar 2012 Posts: 1,879 Location: USA Expertise: I like coffee
Espresso: Gaggia Classic PID Grinder: Preciso
Posted Thu May 17, 2012, 4:52pm Subject: Re: Pressure Profiling Mod - (originally "What kind of valve do i need?")
I have been reading with interest. I thought that some of the Gaggias that used the silicone with braid reinforcement had leak problems at the connections. The difficulty is the clamp/tubing/hardpoint connection.
i didnt realize how much these things would cost. ugh. about a hundred bucks. the mcmaster is about 20 bucks cheaper so i went with that one. they're also sorta local to me(santa fe springs) so it works out a bit better.
so...now i need the OPV(waiting on chris') and the shuttle valve(waiting on local quote or just order online). looks like i have at least about 60-70 more bucks to spend before i have everything i need. ugh.
all in all, it looks like it's gonna cost about 200 dollars just in parts to get this working. ugh. it's painful to add it up.
time for bed. it's be a long day with this pressure profiling nonsense.
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