Lift Station Maintenance for the Complete Idiot - Pump Ed …

[Pages:10]Lift St at ion Maint enance for t he Complet e Idiot

St eve Cot t rell

Enco S out hwest , Inc. 14 2 6 Pueblo Drive

Boulder Cit y, Nevada 8 9 0 0 5 ( 70 2 ) 2 9 3 -4 13 4

Copyright 19 9 5 All Right s Reserved

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Don't Hat e M e Because I'm a Lift S t at ion

Nobody ever put in a sewage lift st at ion because t hey want ed t o. There are very few ot her pieces of equipment t hat are as universally hat ed as lift st at ions. What usually happens when you hat e somet hing? You avoid it like t he plague. What happens when you avoid a lift st at ion? It gives you plent y of reason t o hat e it . The simplest way t o avoid problems wit h a lift st at ion is t o keep an eye on it . Get t o know it and what t o expect from it . Once you get t o know it you will spot t roubles while t hey are st ill small and avoid having bot h pumps give it up at 4:3 0 on a Friday aft ernoon.

This guide will t ake you t hrough t he care and feeding of your lift st at ion. Follow t he recommended procedures and your chances of experiencing a t ot al lift st at ion failure will be great ly r ed uced .

The Basics

The lift st at ion is really pret t y simple. The wet -well is t he basin t he pumps sit in. There are t wo pumps, each wit h it s own check valve and gat e valve. The check valves st op flow from coming back int o t he st at ion when t he pump shut s off and also keep one pump from

pumping back t hrough t he ot her. There are four cont rol float s in t he wet -well. These have a lit t le mercury swit ch in t hem (like a t hermost at ). The lowest float is t he off float , t he next highest t he lead float , and t hen t he lag float ,

and finally t he alarm float . We'll discuss float s in det ail lat er. They send a signal back t o t he cont rol panel t hat t urns on t he select ed

pump. In normal operat ion, t he pumps swit ch back and fort h aft er each pumping cycle. A device called an alt ernat or select s which pump will be t he lead pump. When t he wat er level reaches t he lead float , t he lead pump is t urned on. The ot her pump becomes t he lag pump. If t he wat er level cont inues t o rise it will act ivat e t he lag pump. Then bot h pumps will st ay on unt il t he wat er level drops low enough t o make t he off float shut off. When t he pumps shut off t hey reverse roles. The lead becomes t he lag and vice versa. This is how t hey back each ot her up in case one becomes clogged or quit s for any reason. As we will see lat er, it 's also t he reason you could go along not knowing one pump has quit unt il t he ot her does and you have a major problem on your hands.

In t he cont rol panel t here is a circuit breaker, a mot or st art er or cont act or, and an overload for each pump. High volt age runs t hrough t hese component s. The pumps get t urned on

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and off by sending low volt age (110 volt s) t o t he coil of t he cont act or. The cont act or has point s in it t hat are pulled t oget her by an elect romagnet . Power t o t he elect romagnet (or coil) is also run t hrough t he overload prot ect or. If for some reason t he pump draws t oo much current (amperes) t he overload will open and t he pump will shut down. Aft er t he overload has cooled it can be reset . If t he pump draws an ext raordinary amount of current , like in t he case of a dead short , a locked up pump, or wat er in t he mot or, it will t rip t he circuit br eaker .

A print ed circuit board cont rols t he low volt age operat ion. The float s connect t o t his board.

Each pump has a hand-off-aut omat ic

(HOA) swit ch. In t he hand posit ion t he

pump will run no mat t er what t he

wat er level is in t he wet -well and keep

running unt il you t urn it back t o off or

aut omat ic. In t he aut omat ic posit ion

t he pump is t urned on and off by t he

float swit ches. There is also a cont rol

circuit mast er swit ch below t he HOA

swit ches t hat must be on for t he

pumps t o operat e. The cont rol circuit

will operat e even if t he circuit breakers

are off.

This is useful for

t roubleshoot ing wit hout t urning t he

pumps on and off. The cont act or will

st ill pull in, but wit hout t he high

volt age coming t hrough it t he pump will not operat e.

There may be several opt ional feat ures in t he cont rol panel such as elapsed t ime met ers (hour met ers), seal failure indicat ors, high wat er alarm, phase prot ect ors, et c. If you are not sure what somet hing does, you can check t he elect rical schemat ic on t he inside of t he door or give us a call.

Some pumps require capacit ors t o get t he mot ors st art ed. If you have a single-phase cont rol panel you

will have capacit ors. There will be a st art capacit or t hat will usually be

black, a run capacit or t hat will usually be silver, and a lit t le square brown box t hat is t he st art relay. Capacit or circuit t roubleshoot ing is covered in det ail in t he cont rol panel manual in t he appendix.

Spend some t ime looking around t he cont rol panel. Do not put your hands, or a screwdriver, or anyt hing else in t he cont rol panel unless you are sure t hat t he power is off and locked out . Check it wit h a volt met er. Don't ever assume t hat t he power is off. Check and double-check it .

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Down t o t he Nit t y G rit t y

Now t hat you have a basic idea of how t he lift st at ion works we need t o look closely at t he ways you can keep it working day in and day out . As you will see, an invest ment of 5 minut es a day can save you hours of headaches and t housands of dollars.

Rule No. 1 - Check t he lift st at ion on a daily basis. This is no big deal, t akes about t wo minut es, and is t he best insurance policy you can buy. Get in t he habit of checking t he lift st at ion first t hing every morning and t he last t hing at night . Even if you just st opped by t o say hi t o your lift st at ion you would be doing yourself a favor. Pret t y soon you would get used t o t he sight s and sounds and smells and know when somet hing out of t he ordinary was going on. But t o get t he most out of your visit you need t o look at a few t hings every day.

Care and Feeding

The single most import ant t hing you can do t o keep t he lift st at ion alive and well is t o read and record t he hour met ers every day. The hour met ers show how long each pump has run. You will have t o open up t he cont rol panel t o do t his. When you do, be careful not t o t ouch any of t he

elect rical component s. Unless t he panel is equipped wit h an aut omat ic disconnect device t here will be live volt age and it will be in t he 23 0 t o 4 6 0 volt range.

A calendar is perfect for keeping t rack of hour met er readings and ot her informat ion about t he lift st at ion. Writ e down t he current met er reading and subt ract t he one from t he day before for each pump. Try and do t his at t he same t ime each day. Don't just writ e down numbers.

The pumps should alt ernat e each cycle. If everyt hing is working right t he pumps will have each pumped t he same number of hours in t he t ime since you last read t he met ers.

Every lift st at ion will be different . Some run 15 hours a day (7.5 hours per pump) and some only run 0 .6 hours (0 .3 hours per pump). Aft er you do t he readings for a week you will have a base line t o work wit h. Depending on t he t ype of project you have, you may get t he same number of hours each

day. A full apart ment complex would have t his t ype of flow. Or t he hours may vary. An office/warehouse complex would have higher flows during t he week and maybe no flow over the weekend. Get t o know what t o expect .

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Hour met ers in cont rol panels can work t wo different ways. In some t he hour met er for t he pump keeps running even if t he breaker or overload is t ripped and t he pump is being called for. In ot hers t he hour met er shut s down when t he pump t rips out on an overload. See what yours do. Turn off t he circuit breaker t o one pump and t hen t urn t he hand-off-aut omat ic swit ch t o manual.

Look at t he hour met er closely and you will see t hat it is running. When you are sat isfied t hat it is running push t he t est (or t rip) but t on on t he overload and check it again. If it is st ill running t hen you can diagnose a bad pump as being t he one wit h t he most hours on it .

For example, Pump No. 1 had 6 .3 hours on it over 24 hours and Pump No. 2 had 14.8 hours. Somet hing is wrong wit h pump No. 2. It 's being called for and t he hour met er is running but it is not pumping. The hour met er keeps running unt il t he wat er level get s high enough t o call for t he lag pump and t he wet -well get s pumped down. On t he next cycle, No. 1 will be t he lead pump and will pump O.K. so t he met er get s t he normal amount of t ime on it . If your hour met er shut s off when you t rip t he overload, t he pump wit h t he least amount of hours on it will be your t rouble pump. You

need t o know t his t o use t he hour met ers as a diagnost ic t ool. The hour met ers will show you a problem before it becomes an emergency. Let 's look at a couple sit uat ions and see how t he hour met ers can save t he day. Suppose you have a brown out one aft ernoon and t he volt age get s low enough t o t rip out Pump No. 1 on an overload. The power get s back t o normal before t he wat er level reaches t he lag float so Pump No. 2 picks up t he slack. The next morning you see t hat Pump No. 1 has t wice t he hours

on it t hat No. 2 does (your panel is t he t ype t hat t he met er keeps running even t hough t he pump is not pumping). You do some basic t roubleshoot ing, reset t he overload, and everyt hing is back t o normal. No sweat . No emergency.

Now let 's look at t he ot her side of t he coin. You get busy and blow off checking t he lift st at ion for a couple days. It 's your day off so you head t o t he mount ains. The brown out has t ripped No. 1out but you don't know it . That aft ernoon a plast ic bag get s sucked up int o Pump No. 2 and t rips t he breaker. A couple hours lat er t enant s st art complaining about sewage coming up in t heir floor drains and bat ht ubs and someone not ices t he light blinking on t he lift st at ion. You are in t he mount ains, t he manager doesn't know anyt hing about t he pump

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