RO/DI any experience
- Thread starter Newsalth2o
- Start date
SpectraPure
.Registered Member
The handheld TDS meters are great for portability, especially when checking multiple storage tanks and such. On of our in-line meters (being dual probes meters), would allow you to monitor the TDS coming out of your membrane and out the DI for maximum convenience.
This way you'd know if there is a higher ionic load going to your DI as fluctuations in TDS have been reported through different parts of the year here in AZ. Then there's the benefit of having a visual of when your DI is exhausting, without having to rinse vials, turn ball valves and such.
Hope that helps,
Shane.
SpectraPure
.Registered Member
WOW! I'm curious to know how much your water to waste ratio changed from the inherent back pressure of adding all those DI stages.
Shane.
Newsalth2o
New member
SpectraPure
.Registered Member
In a simple model, rejection and production are determined by knowing the delta P across the membrane. In an RO system, this is assumed to be the inlet pressure gage preferably on the membrane itself (as pre filters also drop pressure too) and the outlet pressure is assumed to be zero (or atmospheric).
But we connect these RO membranes to DI systems, right?
YES!
So now what?
With DI stages added to your RO system additional pressure drop is added over the simple model mentioned. Since the RO now sees a "back pressure" from added DI stations, the output of the RO is no longer be assumed to be zero or atmospheric. Thus, production calculations are effected, as re optimal settings for waste rejection (which ultiately effect longevity of your membrane and the rejection performance).
You can see the calculated the benefits of booster pumps on RO rejection and RO production (for example, here http://www.reefcentral.com/forums/showthread.php?t=1234209
So it can be shown that your production and rejection will be impaired by additional pressure drop from DI stages.
This is why production as measured in DI water production can be so different than that of the output of the RO system (to atmoshere, ie no back pressure).
In general, higher inlet pressure within the system inlet ratings and low pressure drop (yet maintaining your desired removal efficiencies and speciation) in a RODI system is a good thing. Too much of a good thing and it trickles to a stop.
Fun, isnt it?
Bruce
But we connect these RO membranes to DI systems, right?
YES!
So now what?
With DI stages added to your RO system additional pressure drop is added over the simple model mentioned. Since the RO now sees a "back pressure" from added DI stations, the output of the RO is no longer be assumed to be zero or atmospheric. Thus, production calculations are effected, as re optimal settings for waste rejection (which ultiately effect longevity of your membrane and the rejection performance).
You can see the calculated the benefits of booster pumps on RO rejection and RO production (for example, here http://www.reefcentral.com/forums/showthread.php?t=1234209
So it can be shown that your production and rejection will be impaired by additional pressure drop from DI stages.
This is why production as measured in DI water production can be so different than that of the output of the RO system (to atmoshere, ie no back pressure).
In general, higher inlet pressure within the system inlet ratings and low pressure drop (yet maintaining your desired removal efficiencies and speciation) in a RODI system is a good thing. Too much of a good thing and it trickles to a stop.
Fun, isnt it?
Bruce
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