Why do you not recommend using galvanized pipe on your water softeners?

A question often asked is materials of construction for water softeners. Summarized below, Res-Kem's Director of Engineering, Bob Hader answers in a recent "Engineering Notes":

"Corrosion can occur with any type of piping depending on the application, environment and precautions taken to prevent corrosion. We at Res-Kem find that steel piping with iron fittings offers the best balance of corrosion resistance and cost.

First, softened water has not shown to cause any more internal corrosion in steel or galvanized piping than hard water. Corrosion, which does occur with unlined steel tanks, piping & fittings or galvanized tanks pipe & fittings is generally caused by other factors. Some of these are pH, temperature, dissolved gasses (oxygen and carbon dioxide) in the water, contact with air and galvanic action.

The greatest contributor to corrosion we see with water treatment equipment is on the exterior surface of tanks, pipe and fittings. Given most water treatment is in areas where the air is warm (boiler rooms, laundries, non-air conditioned utility rooms) and the water is cold; condensation forms on everything. Uncoated or unprotected steel tanks, steel piping and cast iron valves will rust and corrode. Galvanized piping is not free from this problem. The corrosion will take place at the threads (which are not galvanized)."

Here is the complete Engineering Note.

What is an Empty Bed Contact Time (EBCT)?

We receive many questions on calculating the Empty Bed Contact Time as follows: "How do I calculate the "Empty Bed Contact Time" for sizing my carbon bed?"

Our Answer:
Calculating the Empty Bed Contact Time, EBCT, is fairly easy to do once you know that the EBCT has the units of time, and usually presented in minutes. You need to know the volume of the carbon bed in your vessel and the flow rate. Just watch to be certain your units are consistent.

For the units commonly used in the United States:
V = Carbon Bed Volume (cubic feet)
Q = Flow Rate (gpm)
C = Conversion Factor (7.48 gallons/cubic foot)

EBCT= (V x C )/ Q

The EBCT for some common contaminants are:

Chlorine = 2 minutes
VOC's = 7 minutes
Hydrogen Sulfide = 4 minutes

Am I Using Too Much Water During My DI Regenerations?

We received a question on the amount of regeneration water an operator is using:
"Is it ok to use about 250 cubic meters of water for regenerating double-bed demineralizer system with a 125 gpm system capacity (132 cu.ft. cation volume and 55 cu.ft. anion volume)?"

Our Answer:
"250 cubic meters of water is about 66,000 gallons. Assuming you use around 20 gal/cu ft for backwash, 30 gal/cu ft for slow rinse, and 45 gal/cu ft for fast rinse; you are only using around 17,400 gallons of water total, not including dilution water for acid and caustic. Even if you round it up to 20,000 gallons, that is a long way from 66,000 gallons. You are using over three times the typical amount of water. You should work with your resin supplier to test the capacity of the resin and detect any possible foulants. You may have to clean or replace the resin."

Bacteria in RO System

We received the following question on our web site:
"I am getting some bacteria coming out of my RO that I was not getting before. How can I clean the membranes."

Our Answer:
"You can use a product known as Minncare(R) or Oxonia. Both are sanitizing agents made up of hydrogen peroxide and peracetic acid. Dilute to 50 - 100 ppm, pump through RO, soak for an hour and rinse out. Please check with you membrane supplier and Minntech/Oxonia to insure compatibility with your RO membranes. Both Minncare and Oxonia are on the web."

"Take my CARBON ... PLEASE!"

SPENT CARBON RETURN

Almost since our founding in 1983, Res-Kem's Technical Services Group has removed (rebedded) spent media, ion exchange resin and activated carbon, from industrial water treatment systems. Part of the rebed service usually includes removal of the spent media from the customer's site. Companies who regularly deal with waste know that getting rid of spent ion exchange resin or activated carbon can be a fairly complicated process. We take this hassle away from our customers.

For years, Res-Kem sales people have known our residential and commercial water treatment dealers have the same problem - how to properly dispose of spent activated carbon that accumulates over time. Res-Kem and Calgon Carbon have teamed up to help our water treatment dealers with spent activated carbon return. As a service to our dealers, Res-Kem will accept spent carbon at the Aston, PA facility. Call for pricing. Click here to download the PDF of the fine print.

Launching new Res-Kem website and Res-Kem blog!

The new Res-Kem website is now live!

And with it - the new Res-Kem blog, where we will talk about many topics of interest to the water treatment community, projects for some of our customers, and trends in the industry.