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Confessions of a Chemical Feed pump Manufacturer   04/30/2003 If you are in the water conditioning or water treatment industry, manage a  store, or are an installation professional, odds are excellent you know  more than most about pumps.  Here are a few things I'm fairly sure you  didn't know.  Most adults own at least six pumps: Fuel pump Washing machine (water pump) Oil pump Vacuum cleaner Dishwasher (water  pump) Air conditioner  I'm sure I've left some out, but you get the point.  Pumps are a very  important part of nearly everyone's lives.  Below I've listed some  historic information on pumps.  Pumps are not a new technology – only the power used to drive pumps (and  control) are new.  Pumps date back to Alexandria (Greece) 100 BC; animals,  yes-even humans, powered pumps.  Christopher Columbus (1451–1509) used bilge pumps on his ships (pumps were  made out of lead, with leather strips for flapper type check valves).  It  was written that he said "an efficient bilge pump was the most important  piece of equipment on a ship".  I believe now we've established the  historic aspect of pumps, it's important we understand the basic  classification of pumps.  Today's water conditioning & w/ treatment installations include one or  more of the above pumps.  Centrifugal pumps are used for pumping large  amounts of water, of particular importance in water recirculation.  Piston  pumps are of importance in water reclamation, such as reverse osmosis  systems, due to their very high pressure capability.  Displacement style  pumps (diaphragm, or peristaltic), is a common way to pump chlorine, or  other water treatment chemicals, we know them as; chemical feed pumps,  metering pumps, chlorinators or injection pumps. Now we've established the  importance of pumps in our lives and in particular, the water conditioning  & w/treatment industry, allow me to focus in on pumps used for chemical  delivery in our industry.  Although these pumps are properly called  displacement, pumps (remember) both reciprocating diaphragm, and rotary  peristaltic, in this article for diaphragm pumps I will use the name;  chemical feed pump, the rotary peristaltic is often referred to as a tube,  or squeeze tube pump, I'll just use the name peristaltic pump.  Now that we've covered some of the history, I'd like to share some of what  I've picked up over the years. Working for a well-known chemical feed pump  manufacturer for thirty-three years has taught me quite a lot.  Some of  what I have learned may be valuable to you, a water conditioning &  treatment professional. I would like to clear up some myths, or  assumptions I've been asked about from time to time. Do you as a  manufacture build in planned obsolescence? Nothing could be  further from the truth; to the point, the question is almost humorous.   When a particular chemical feed pump is designed, there are countless  kinds of destructive testing conducted.  We deliberately try to cause  the product to fail. Product improvements are an ongoing process that  just never ends. When we force a breakdown, that particular part or area  is redesigned until it's corrected.  Metering pumps should be trouble free. Of all your  equipment you work with, the metering pump will require the most  attention. The model you purchase is important, and the brand  reliability, remember you are dealing with far more than a mechanical  pump, you are dealing with; water chemistry (ph  & chlorine levels,  to name a few), the possibility of serious bacteria, water temperature &  pressure, and a multitude of other factors. When you put them all  together, there is far more involved than a chemical feed pump. The  "perfect chemical feed pump" will not overcome a poor installation. If  any of the above items are neglected your job will become infinitely  more complicated   Which type of pump is  better, peristaltic or diaphragm? As a manufacturer of  both I can tell you with some expertise they both have their strengths  and weaknesses. I will also tell you there really is no definitive  answer.  It would be similar to asking what's better a Jet pump or a  Submersible pump?  Peristaltic pumps are a bit easier for the novice,  but if not maintained are far more problematic than diaphragm pumps. If  you have a good working knowledge of diaphragm feed pumps, and  understand the basics of maintaining check valves, this type pump is  more cost efficient.  I believe in choice, and I'll let the market  decide that question.    Chlorine is on its way out. We have a Love/hate  relationship with Chlorine. This is a case where the good definitely  outweighs the not so good.  Don't even try to imagine our lives  completely without chlorine as a disinfectant.  Alternative forms of  disinfectants play a larger roll in our industry, and that is a good  thing.  However, make no mistake chlorine is still the disinfectant of  choice in our industry, it simply works well and the cost benefit isn't  worth arguing. Most water  conditioning & W/treatment professionals have their favorite type of  chlorine.  As a manufacturer, I do too.  Let's go over them.  Liquid  chlorine (sodium Hypochlorite) is usually purchased at your favorite  dealer/distributor, or chemical company, some regions the chemical is  delivered on a route basis.  This industrial strength chlorine runs  anywhere from 9% to 15% active chlorine. The chlorine you purchase at  the super market is considerably weaker about 5% chlorine.  Sodium  hypochlorite, or liquid chlorine is the chemical of choice for most  mechanical chlorinators, some will argue that point, but for the most  part hands down its liquid chlorine.  The problem with liquid chlorine  is; it is heavy, cumbersome, and transporting it can be hazardous.   Liquid chlorine weakens over time.  Dry (chlorine) or calcium  hypochlorite also has its advantages, and disadvantages.  It is  certainly easier to store and does have a longer shelf life.  Some of  the challenges are obvious; you have to mix slurry (dry chemical &  water), so it can be pumped.  The amount of undissolved solids will over  time foul check valves, and plug injection fittings.  Peristaltic pumps  are recommended if you choose to pump chlorine slurry.  Peristaltic  pumps easily handle chlorine slurries, because they have no check  valves. Some tips on maximizing the  performance of your mechanical chemical feed pump (diaphragm, or  peristaltic style) Keep variables to a minimum.   Such as, chlorine strength, type of chlorine used, and the feed rate  setting on chemical feed pump.  Example; if you keep the chlorine  strength consistent, during the summer months, you'll need to increase  the amount of chlorine to be fed. On a peristaltic pump, adjust the on  time up (pump longer), with a diaphragm pump increase the cam setting,  or pulse rate.  If you tamper with chlorine strength (usually a problem  with slurries), and chlorinator feed rate, you will just drive yourself  crazy.  Minimize your variables.   Avoid running chemical container  dry, while the pump may not be mechanically harmed, pumping air will  cause the valves to build up a residue of dried chlorine (salt).   After changing out chemical  containers make sure, the chemical feed pump is primed and most air is  purged out of the pump head & discharge line.   At least every six months  inspect, and if necessary, replace the diaphragm.  Also, inspect the top  and bottom valves; clean or replace. If you are using a peristaltic  feeder, change pump tubes out regularly, Also keep your eye on the  roller assembly; the rollers do require periodic lubrication, and  replacement.  Rollers that are frozen, not rolling correctly will  dramatically shorten the life of the pump tube.   Keep spare liquid ends  (assembled pump head kits) handy, as we all know Murphy's Law, "Problems  usually occur at the most inopportune times", it's far easier to replace  a diaphragm and pump head assembly with valves (usually just 4 screws)  than detailing every o-ring and ball seat.  Using peristaltic pumps?   keep pump tubes and roller assemblies on hand. Time is money.   Inspect the foot valve strainer  quarterly, or as frequent as necessary.   Chemical feed pumps are easy to  prime when the discharge (pressure) line is removed or vented.  After  the pump is primed re-attach the discharge line to the top pump head  valve, or close the vent relief.   Keep the pump room clean & well  ventilated – Too many pump rooms are a mess.  The rooms should be neat &  clean (not a storage area for junk) spare parts should be available at  the site.  An installation, instruction booklet should be mounted on the  wall at or near the chemical feed pump, this will have a parts schematic  complete with part numbers.    Always wear eye protection when working on chemical injectors or  when changing out containers, or adding chemical. This is something that  cannot be over stressed.   Avoid changing chemical brands  without researching the compatibility regarding your chemical feed  pumps.   A flow indicator installed on  the suction tubing of your injector is an outstanding diagnostic tool,  at a glance you can see if the pump is working properly. Some  manufacturers offer them as standard equipment.   Never mix different chemicals in  the same solution tank.   Never inject chlorine and pH  adjusting chemicals near one another, always use caution.   Your Chemical feed pump must  shut down when the water recirculation pump is not running.  The  chemical feed pump should operate in concert with the water pump, never  by itself. Chemical feed pumps – Double  ball check valves just work better than single ball check valves.   The weakest side of a diaphragm  chemical feed pump is the suction side (the ability to draw chemical),  always keep your suction run as short as possible (5' or less).   Discharge runs are not as critical.   Most all warranty and out of  warranty work is related to poor maintenance.   Peristaltic pumps have an  amazing ability prime, up to 18' (without discharge backpressure), it's  true, but please keep the suction run a short as possible.   Your pumps injection fitting is the single most neglected part of your system. When your injection  fitting begins to clog, the chemical feed pump works harder & harder to  overcome the blockage (sound familiar). Change or clean them regularly.See more on this...   Peristaltic pumps – Are easier  (more forgiving) to use, but if neglected could be a serious problem.   Pump tubes need to be changed with regularity; many are not & eventually  could leak corrosive chemicals.  Changing a pump tube is not  complicated, and just takes minutes.   Peristaltic pumps – Older  peristaltic pumps benefit from changing out roller assemblies, as these  rollers age (wear), slowly you lose critical squeeze tolerances and the  pump gradually will lose the ability to inject chemical.  Often the pump  tube is blamed, but the problem is really the roller assembly. Suction & discharge tubing needs  to be replaced regularly.  This is one area where I see widespread  neglect.  Tubing is available practically everywhere and is rather  inexpensive.   Chemical controllers (pH, ORP &  TDS) are of growing importance to our industry. This is an area you  absolutely need to hire the most qualified, and service after the  installation is an absolute. Most controllers work well with chemical  feed pumps; Stick with the industry leaders, those controller companies  with a proven track-record.  Avoid elaborate so-called turnkey systems  that claim to do everything. Caveat emptor.   There is no perfect chemical  feed pump or system – No matter the cost or what you were led to  believe.  The success of a particular job, or system is directly related  to the installer & quality of equipment,  but most importantly how the  equipment is installed & maintained.  As a manufacturer, we do our best  to manufacture the finest equipment, but we are only as good as those  who do the installation, service & maintenance work. In summary, pumps have a very long  history dating back 100 BC.  Pumps are crucial to our lives, and  particular importance to the water conditioning/treatment industry.