February 09, 2017

Commercial System Considerations

By Rocky Hoffman

What are Commercial water softeners and filters?  How do you size them and select the correct system for an application? The intent of this article is to help you understand the basics of site evaluation, equipment selection, and installation recommendations. Uncommon sense and out of the box thinking may be needed to assess a potential job, whether this is a new installation that has been designed by an A&E firm, or if you are looking at an existing building that needs to have the equipment replaced.

Commercial systems may be as small as a 1cf water softener feeding a small restaurant water heater, and as large as you may need for a hotel, hospital, large restaurants, car washes, apartments, etc. We are primarily concerned in this article with Commercial systems and not with Industrial systems such as petro-chemical plants or large manufacturing facilities. However, some of the same basic questions need to be asked.
What is the water requirement? How many GPM of softened or filtered water is needed for how many hours each day? Where is the system being installed? Is this a new installation or is this replacement equipment? What is the access to the installation location? Have you measured the doorways and hallways and elevators (ie. A 36” door may only have a 34” opening due to the frame and stops)? Is there access at ground level or is there a loading dock? Is the installation in an equipment room that has exterior access or is the installation in an inside room, basement, or upper level? What is the pipe size of the supply water? What is the static line pressure for the water entering the building? What is the flowing pressure of the water at the required flow rate? Where is the closest drain, and is it capable of handling the backwash water flow rate? If not, is there a plan to catch the BW water and pump it to an acceptable drain? What is the main pipe connection material and size? Is there an existing “header” with bypass valves to accommodate the installation, or do you need to provide for this in your quote?  What is the ceiling overhead height of the room? Is there piping or duct work overhead in the installation area that minimizes or interferes with the equipment height? Is the room adequately sized for the installation of the specified equipment including any appurtenances such as chemical or brine tanks, etc?  Is the room large enough to allow future service of the equipment installed in the room, including access to manways for media exchanges, removal of top mounted control valves, removal and replacement of membranes or filter cartridges? What is the access for future media replacement or salt deliveries if this is a softener?

Check and double check these questions and any others you may think of on your own.  In addition, remember to check and supply equipment and piping systems that meet or exceed local plumbing codes.
The next step is to “size” the system based on the required flow rates and amount of filtered or softened water needed between backwashing or regenerations. Filter systems can be selected from your OEM’s equipment charts based on flow rates needed and BW water available. Remember that the Backwash water generally needs to be clean, filtered water. Multi-tank filters may be required to supply the GPM of BW water needed for an individual tank, while still supplying filtered water to service. You must consider the type of filtration and media needed, and select equipment that will give you adequate empty bed contact times for contaminant reduction, or effective filtration to an acceptable micron size. 

Water Softeners may require calculations to determine how many grains capacity are needed per 24 hours (or time between regenerations), and based on a desired salt dosing. You must consider the raw water hardness and take this into consideration when sizing or selecting a water softener system. A “rule of thumb” is to size a water softener so that each tank in the system will regenerate every three days. In some cases, you may have to settle for more frequent regenerations and smaller systems due to space constraints. 

Your OEM can and should be able to help you select equipment if you supply them with the necessary information. 
Now that you have determined what your customer needs and you have selected the equipment, let’s discuss installations.  Refer back to the BASIC QUESTIONS section and review where this system will be installed and what pipe materials will be used.  The installing contractor is responsible for placing the equipment in the correct installation location and for all piping connections to the system.  This applies to skid systems, and also to free standing systems where you may have individual floor mounted tanks.  
Is your OEM supplying you with a “plug and play” skid mounted system where you or the installing contractor only has to plumb the inlet/outlet and drain connections, and make the electrical hook up?  If so, you will need to double check their supply lines and all connections prior to start up.  Some companies prefer to “wet test” the systems prior to loading the media, in case there are any piping or tank issues resulting from shipping and handling that need to be corrected.  This recommended procedure is also for free standing tank systems.   Follow all recommended media loading procedures.   After the media is loaded, the system then needs to be started up and placed into service.  Double check all flows and especially the backwash and fast rinse flows to drain to insure that you are not losing media to the drain from an incorrectly sized BW flow controller, or during “fast rinse” from a broken bottom distributor inside the tank .
Steel tank systems are often supplied in larger installations or where tanks built to ASME code standards are required.  Piping may be Schedule 80 PVC, copper, galvanized, or stainless steel.  Regardless, all piping must be to local plumbing code and must not have connections or pipe hangers of dissimilar materials that might cause electrolysis and potential failures.  Steel tank systems may have “hard piped” unions, flanges, couplings, or Victaulic connections.
Fiberglass tank systems require special piping considerations.  The fiberglass tank manufacturer’s installation and handling guidelines must be adhered to or the tank warranty is void.  Structural Fibers, a Pentair company, has an excellent booklet that is attached to each of its larger sized tanks.  This booklet is re-printed and available on the Nelsen Corporation web site.  Basically, it states that plumbing connections to their tanks requires “flexible piping connections”.  OR you must use a right angle calculated pipe run length from the center of the tank to the tank exterior for side mounted piping and valves to allow for the expansion and contraction of the tanks during service and regeneration.  This required flexible piping allows the tanks to grow in width and height without causing tank or piping failures.  Failure to make a flexible pipe connection will void their tank warranty.
Your OEM should be able to supply you with flexible connections for systems with fiberglass composite tanks.  If you are buying systems with top mounted control valves, remember to install flexible piping connections.  Di-electric stainless steel flexible piping connectors are available in 1”, 1 ¼”, 1 ½”, and 2”.   Larger flexible connectors are also available for 3”valve systems and should always be installed on 3” control valves mounted on large fiberglass tanks. 
There are many considerations when selling a commercial water conditioning product.  To save yourself time and money, be sure to ask the right questions, and verify the installation location and access.
Please see the following references if you would like to build an in depth library for C&I system information.
Recommended Reference materials:
  • WQA -  Water Processing for Residential. Commercial, Light Industrial by Wes McGowan
  • WQA-  Water Treatment Fundamentals- by Joseph Harrison
  • Practical Principals of Ion Exchange-  by Dean L. Owens
  • Technologies for Small Water and Wastewater Systems-  by Edward J. Martin and Edward T. Martin
  • Betz Handbook of Industrial Water Conditioning
  • The Nalco Water Handbook- Second Edition
  • Water Treatment Principles & Design-  James M. Montgomery Consulting Engineers
  • Alamo Water Refiners Water Improvement Engineering Guide-  compiled by Rocky Hoffman and James Lampkin.
  • Pentair Water Treatment: Pressure Vessel Lifting, Handling & Installation Instructions.  Part# 11967-A Rev 10/97
Rocky Hoffman, Past TWQA President and Board Member. 
38 years experience in C&I Water treatment systems sales, service and installation.
Director of Engineering &Technical Support for Nelsen Corporation, Schertz, TX