Re: Charging a blended gas?
if you can find out the correct charge then that is the best way otherwise charge to superheat in liquid form
Re: Charging a blended gas?
Charge by weight stated in documentation, or charge by subcooling.
Flash gas in sight glass doesn't mean that liquid is not 100% subcooled.
It could flash because of sudden change in pressure drop which occur because of change of shape in line where is sight glass.
For calculation of subcooling, you need to use bubble point temperature of R407C for measured pressure at condenser outlet.
Re: Charging a blended gas?
Quote:
Originally Posted by
james10
if you can find out the correct charge then that is the best way otherwise charge to superheat in liquid form
You cannot charge by superheat system with TXV, since TXV control flow to keep superheat constant.
Re: Charging a blended gas?
Thanks Nike 123. Is it acceptable to check Subcooling before the TXV as most close control units have the compressor inside with the evaporator so charging is done inside a room not outside?
Re: Charging a blended gas?
Yes it is, if there is not significant pressure drop in lines (and parts like filter-drier) from condenser to TXV.
In fact, just before TXV is best place to check both pressure and temperature, since that is place where we want full liquid state.
1 Attachment(s)
Re: Charging a blended gas?
Even though direct charging R407C is allow for some manufacturers those who have composition sensors for three different blends 32/125/134a. If there is gas leak, then their composition and working pressures are changed.
Due to different boiling points, lighter one's percentage reduce repidly. So that you need to drain all the R407C and recharged. And have to charge in liquid phase of course. here is the attached. Hope that will help.
Attachment 6588