Recent content by ashtree

Thanks everyone. A lot of different opinions on what is good, what is workable and what is not. That seemed to be the advice i had generally been getting anyway. Seems like the general consensus is though to put the transformer after the VFD

We are working through the issues on installing 1000 volt motors on well pumps at about 350 metres (1100 feet ) below ground. We have to go to 1000v because of the cable size required to limit the voltage drop at 400volts is so large that we cant fit the pump and the cable down the well. These...

DuPont RO Technical Manual is a good start. However it is technical and requires close reading to develop a full understanding of the subject. https://www.dupont.com/content/dam/dupont/amer/us/en/water-solutions/public/documents/en/RO-NF-FilmTec-Manual-45-D01504-en.pdf Regards Ashtree "Any...

On a single membrane recovery is normally limited to about 15% to avoid concentration polarization. However if you recirculate a portion of the concentrate from that one membrane back to the feed of the membrane it is possible to achieve concentrations up to the solubility limit of the most...

Blurt Its a matter of what is getting carried through to the effluent to be chlorinated. THMs are typically caused by the chlorination of organic matter. Most likely you have more BOD in the effluent than what you had when you were feeding glycerin. A TOC/DOC test of the effluent when using the...

Why is finished water pH important beyond the obvious. If you are worried about corrosion, high pH is not required if you have the appropriate hardness, alkalinity, TDS etc. Higher pH is one way to get the LSI to an appropriate value but its also a balance with calcium and alkalinity. What this...

Wright 44, Do you have any details of the Limestone that you propose to use. Porosity, diameter, roundness? With regards to the water do you know the permeate TDS and the dissolved inorganic carbon As a general requirement you typically need to have an empty bed contact time of at least 20...

PamL This is an excellent handbook which will help with some of the information you seek. https://www.emerson.com/documents/automation/control-valve-handbook-en-3661206.pdf Regards Ashtree "Any water can be made potable if you filter it through enough money"

It would also help to know how much daily, weekly or monthly variation in those water demand numbers. If there is considerable variation either side of the 100kl/day you may able to get away with 2 ROs smaller than 100kl/day with one running continuously using the capacity in the large storage...

Many pumps particularly if they have a fixed speed motor also offer stroke length adjustment which alters the volume of each stroke or pulse. This can be done manually or by a analogue controlled adjuster to give "automatic" or "remote" control. Stroke length adjustment works well but is not...

Little Inch is spot on. Unless there is a requirement for flexibility in operation in terms of flow then the overall savings are marginal. But because no one can select pumps properly anymore a VFD is typically installed because you can normally get the output you want at some speed. Maybe that...

Thanks EdStainless UF membranes can tolerate reverse pressure during backwash so i would expect these to be okay. Regards Ashtree "Any water can be made potable if you filter it through enough money"

I am setting up a pressure decay test (PDT) on a UF plant. In simple terms a PDT involves pressurizing with compressed the feed side of the membrane to about 5psi ,locking off the valves and looking at how quickly the pressure decays. This assumes that if a lumen is broken the pressure will leak...

RO membranes do not like being unpressurised on the feed side and having pressure on the permeate side of the membrane . Typically this is recommended to not exceed about 30kpa (4.5 psi approximately). Its not about water hammer or surge , but about protecting the membranes from back pressure...

I agree with TiCl4s comments and you should also check what happens if you lose air pressure. Regards Ashtree "Any water can be made potable if you filter it through enough money"