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Blowing down New air lines

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  • Blowing down New air lines

    I put in New air lines in my shop this week. I cut and threaded new lines and put tees where I wanted them. I left a valve in the end, low point drain.

    As a matter of habit I aired the compressor up when all the lines were hooked, took a rag and put over the valve and blowed it down twice before hooking it to my bridgy.

    I got about two dozen small shrapnels out of the line. Without the rag they would have been bullets. If they had went to the regulators, oiler, cool mist unit on the bridgy they would have been much more trouble.

    Might help someone else, so I posted it.


  • #2
    That's always the lest operation before putting a piped system on-line: blow it down with as much volume as you can muster. Yours was a shrewd move, David.

    My dad was a marine pipe fitter in his younger days. He told me in 1954 when commissioning a new ship they hydroed, tested, and finally put the then high technology 1200 PSI steam plant on-line. The last item was to put a fine mesh stainless steel strainer bag in the basket strainer. Come time to test engine the throttle man gave it 5 seconds 1/3 ahead followed by 1/3 astern. The ship surged briefly agaisnt its mooring lines.

    In the middle of this test down through the steam pipes came a hell of a clatter that crashed to a stop at the basket strainer. Instant panic mode. Everyone knew what had happened: foreign object in the steam line. Stop all, secure the boiler, hit it with cold feed, secure the root stop, the main engine stop, open the drains, run in circles, scream and shout. The ship's force fetched wrenches and opened the strainer. Inside was the wreckage of a Thermos bottle battered by its passage through a hundred feet of steam line, a dozen bends and a forty mile and hour crash at the strainer. Whose thermos? Dire threats. No-body stepped up to 'fess.

    This led to opening every steam valve in the line for inspection. Hundreds of thousands of dollars in labor and materials and a week of delay. Yup, a preliminary blow-down could have saved Uncle Sam a ton of money. OTH it could have been the inlet throttle and the impulse stages of the main engine that took the beating instead of the strainer. At least they had the strainer.

    [This message has been edited by Forrest Addy (edited 01-05-2005).]


    • #3
      Forrest, My grampa died from welding inside the holds of "liberty ships" it paid more money to weld inside the hold.

      He died of lung damage. two ways to look at that, I didn't have a grampa growing up, but WE did win that war.

      I had a stepgrampa that treated me allright.

      I also learned the meaning of HOT ROD. You'd get a jet rod redhot then jam it into the ribs of a smart-mouth or troublemaker and he'd run as fast as hell.. Also then gave to the "cut downs" Cars they made. Remove weight and it goes faster.

      He had a Indian chief motor on a Harley frame. The indian had more power, the harley was lighter, so simple math made it fast.



      • #4
        Speaking of blowing down lines, if anyone uses hydraulic lines on equipment and you replace one, be sure to blow a pig thru it to clean it first. When they cut hose with a cutoff wheel, all sorts of junk will stick to the insides of the new line and air alone will not clean them 100%. Hydraulic oil WILL flush them clean... possibly moving the crud into everyplace except the filter.
        Location: Saskatoon, Saskatchewan, Canada


        • #5
          Dave,good thinking,me I like to see a sintered metal filter inline BEFORE all things like solinoid valves,pilot controls and that sort of thing.They keep all the trash that develops over time from ruining air systems.
          I do know the little euro-air logic controls won't take so much as a fart going through them and survive.
          .5 micron sintered bronze filters solved the problems on the last system,saved the company $$$$$$,I was for a brief period wearing a big red S on my shirt
          I just need one more tool,just one!


          • #6
            The old PID pneumatic-steam control systems used a small orifice and tube that flexed with flow.

            Any water and they had to be recalibrated as they distorted the tube.

            Plant air lines during shut-down for Christmas or the 4th of July always filled with water. Blowing down the airlines before start up never occurred to any of the plant maintenance people. Each year, same deal. I love the electronic digital controls. Fisher steam valves still get a lil haywire thou.

            I got to work around the clock for days after both the shutdowns. I can still hear that stinking lil pager going off on grannies hand carved nightstand (I inherited)

            I recieved 27 pages in one night and got fired for not completing all of them. One was a local millionaire who called cussing me. I got fired for my reply to him.