Near Intersection of I-35 & I-90 Southern Mn. | amstech - 4/3/2010 16:16
I guess from now on I will just keep my opinions to myself and let the other experts offer free advice. I have people pay me for what I think so I will just stick with that plan for now.
Got to agree with you, this is the way that Raven recommends. I have heard of situations where a bunch of tee's and check valves are used for the liquid line leading back to the cooler after the section valves. The part I don't like about that arrangement is the mess of tee's and check valves needed. The other part that I don't care for with check valves is the fact that they will have a certain pressure drop which may reduce the flow to the cooler.
This may work just fine under many or all situations. After all, if the tank pressure is high enough and there is enough back pressure within a system then the cooler might not be needed at all.
We will continue to use a Standard Control Valve followed by a Master ON/OFF valve then the a tee off to feed the cooler. The main line will then lead to the section ON/OFF valves.
Some have implied that we are just trying to sell another $400 valve which is unnecessary. On new large rigs with fancy control systems, injection etc., this $400 is pretty minor in the total picture.
We are now learning in this case that all the knives are leaking (not just those with the vapor tubes on them). The only way I can conceive of this happening is that both new ON/OFF valves are not working properly. This seems highly unlikely but must be the case.
By the way, are the ON/OFF valves installed in the correct direction? If they are installed backwards they will leak like mentioned due to the safety hole in the ball. The valves have a direction arrow on them which is very important. The purpose of the hole in the ball is to allow the NH3 which is normally trapped inside the ball to be released to the outside atmosphere when a repair is needed. When the valve is removed from the system the NH3 inside the ball will bleed out rather than hitting the Tech in the face when he cycles the valve.
In any ball valve, the ball has a slight amount of slop in it. As the ball is turned to the OFF position, the ball is deflected slightly against the seat thus sealing it well. If the valve is mounted backwards, the ball will be deflected alright but the small hole will allow product to pass through the valve. |
GS2 won't fully close Raven NH3 shutoff valve
