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Waterous mechanical vs packing seal

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  • Waterous mechanical vs packing seal

    Can someone explain to me the pro's and con's of the Mechanical spring loaded seal versus the packing shaft seals (Grafoil) on a Waterous pump?

    Use will be in a very rural volunteer department. Not a lot of runs, 50 a year tops. (that actually require a pump)

  • #2
    I'll try to make it short and simple and hopefully not miss too much. The mechanical seal system uses a carbon disc on one side and a ceramic disc on the other with one or the other spring loaded to maintain tension contact. The mechanical seals require no manual adjusting. The mechanical seals are however subject to heat,sand, or other gritty substances that can crack or destroy the sealing action and now requires much more work to replace than the packing seals. The packing seals require adjustment and periodic replacement and if not maintained properly can ruin impeller shafts. They are not however subject to the types of failure that mechanical seals are and much easier to replace in my opinion. We run Waterous pumps exclusively and I find the packing seals to give us very good service. Just my opinion and I know that others prefer the mechanical seal.

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    • #3
      seals vs packing

      The major issue with the ceramic disc from Hale is when most folks get on scene they throw the pump in gear before leaving the cab. This allows the disc to heat up; then when "cold water" is applied when priming it will very often crack or worse the disc so now you cannot draft. We run all packing type seals on Waterous pumps including our newly ordered tanker.

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      • #4
        I think LV hit the biggest thing that I'd imagine you'd be concerned about, maintenance. If I remember right, the mechanical seal has a 7-10 year lifetime (someone know for sure?). Packing is recommended to be changed every 3.

        However, it's not going to be a big deal to replace packing in house if someone knows what they're doing. On the other hand, the mechanical seal (as I remember without looking at the manual) requires the impellor to be pulled out of the pump and is quite an extensive ordeal.

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        • #5
          They guy that fixes our pumps said you need a special tool to put in mechanical seals. I guess it is possible to put them in without the tool but you stand a good chance of breaking the seal. I have heard the mechanical seals do not hold up well for rural departments due to sand and grit in the water.

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          • #6
            Thanks all, we have advised the factory that we want the regular ol packing.

            I think they misordered the pump.

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            • #7
              Originally posted by Catch22 View Post
              I think LV hit the biggest thing that I'd imagine you'd be concerned about, maintenance. If I remember right, the mechanical seal has a 7-10 year lifetime (someone know for sure?). Packing is recommended to be changed every 3.

              However, it's not going to be a big deal to replace packing in house if someone knows what they're doing. On the other hand, the mechanical seal (as I remember without looking at the manual) requires the impellor to be pulled out of the pump and is quite an extensive ordeal.
              The seal manufacturer estimatates life of the seal with "normal" use to be 3-5 years. Out of the three pumps on my department that have mechanical seals the 89 tower still has originals, 96 engine were changed in 2002, and 96 engine/tanker still has originals. New engine this year will have packing because it has a compressed air system mounted on the pump.

              The impeller does not have to be removed but the transmission does to get to the rear seal.

              As explained earlier both have advantages and disadvantages. Packing does not have to be replaced unless it is overheated and does not seal any longer. Packing is probably more forgiving to overheating and is better in areas that have corrosive water.

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              • #8
                Our 93' model pumper has the mechanical seal. It has been replace once. We pump all kinds of water from hydrants to creeks. Don't think we can complain about it. For us the issue of not having to adjust the packing make the mechanical seal the way to go.
                IACOJ - Senior Jake

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                • #9
                  Originally posted by sfd7101 View Post
                  The major issue with the ceramic disc from Hale is when most folks get on scene they throw the pump in gear before leaving the cab. This allows the disc to heat up; then when "cold water" is applied when priming it will very often crack or worse the disc so now you cannot draft.
                  My solution to this is to leave the Pump-to-tank line open and the tank-fill cracked. That way, when I get on scene, I can engage the pump without worrying about water circulation. I don't look for a reason to open the T2P line, I leave it open and only close it when needed (like when I'm drafting).

                  We even have a 1982 Pierce Tanker at my station whose Tank-to-Pump is labeled "PULL TO CLOSE".
                  The American people will never knowingly adopt Socialism. But under the name of 'liberalism' they will adopt every fragment of the Socialist program, until one day America will be a Socialist nation, without knowing how it happened. --Norman Mattoon Thomas, 6 time presidential candidate for the Socialist Party of America

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                  • #10
                    I had a lot of experiance with packing and mechanical seals in the Navy.

                    I prefer mechanical seals. I would get 3-5 years life out of a mechanical seal on a pump that ran 24x7 pumping salt water from a harbor. Trust me, there isn't a lot of room between the bottom of a large ship and the bottom when they are tied up pierside.

                    Mechanical seals is the norm in industry around the world. Your car engine probably has several. Air Conditioning compressor has one for sure. Can't allow any refrigerant into the atmosphere.

                    30 years ago there weren't near as many people with seal experiance, so finding someone to do it properly was a challenge. Yes, it probably isn't something anyone in your department can do. But after 5-7 years good service, changing the seal might be a good time to take a look at bearings a wearing rings (if your pump has wearing rings).

                    Well maintained packing can give good service for a long time. It doesn't take as much skill to replace. It has to leak. You will have drips on your floor, small puddles under your pump. That is the norm in the fire service, so it probably doesn't bother you. I had to personally rebuild too many pumps in the past because some yahoo with a wrench decided he could tighten down the packing just a little bit more.

                    Run a pump dry, blow your mechanical seal, run a pump with too tight packing, burn up your pump shaft. It used to be so common that some pump companies build replacable sleeves on the pump shafts so that when the packing was overtightened you could replace the sleeves instead of the whole shaft.

                    Either product is fine. For a small department with a limited budget, I would choose packing. The reality is that when (not if) a mechanical seal wears out, you will need a decent pump mechanic to replace it. Until it is replaced your engine will be out of service. With packing, even when it is time to get it replaced, it isn't guarenteed that your pump will be out of service until it is fixed. You might be able to limp along with extra leakage until it is replaced. Most likely you will have someone in your department handy enough with a wrench that they can replace the packing.

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