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Thread: compressor bits

  1. #21
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    Quote Originally Posted by Janos View Post
    1). I can’t remember the exact amount. Parceforce (I think) sent me a bill, I paid it, it was delivered.
    2) The MDE filter tower has inlet and outlets marked on the bottom and I connected hoses accordingly. I’m genuinely interested (really!) if you think I have done so wrongly.
    3) Yes. I told MDE exactly what I wanted it for before purchasing.
    4) one of their former employees recommended the, to me ;-)

    Janos
    Lets discuss the critical aspects first and joking aside for the time being.

    Placing a secondary MDE filter stack after a portabe HP compressor presents three major problems.
    First is the type and design of the BPR of the original primary filter.
    Also I should allow Mike F to respond on his reccomendation of the MDE BPR for this application.

    By contrast I couldnt recommend a MDE BPR off the primary stack prior to the secondary because of the method of design and the opening pressure blast caused at the BPR opening pressure setting and pressure surge jet.

    Second the flow circuit for the MDE Series 40,50 models for portable compressors was designed for the older BS4001 air purity. Subsiquently for BS12021 you either have to up the BPR pressure setting and cause more pressure blast problems to the scondary filter chemical or you keep to the original BPR pressure setting and get less filter chemical life than you could.

    Third the opening "throat" of the small MDE filter chemical cartridges (ie the hole diameter of the plastic cartridge) introduces a "pressure jet" effect on the filter chemical this can and will a times disrupt the chemical stack, expand the contact area of the chemical matrix thus reduce the dwell time and lower the cartrige chemical life if you use it as a secondary filter stack

    Four, To answer the "back to front" aspect is that by following the engraved flow direction on the metal filter base this is for primary filtration where in order to extend the small chemical volume life expectancy you use the inside metal wall of the filter tower to act as a cooler to chill the gas and produce water condensate off the vapour dew point thus using the filter as both a separator and filter.

    To achieve this the dirty wet gas flows up ouside the plastic chemical cartridge then down the filter chemical to the outlet port side of the filter base.
    Now as to using it as a secondary filter stack your now "driving" the particulate dust out of the filter cartridge and out into you customers cylinders for one

    One of the very reasons why Bauer and others flow in the opposite direction, up through the filter chemical stack then out at the top and down the inside of the metal tower.
    Ive only just started lots more to come Iain
    Last edited by iain/hsm; 24-11-2019 at 08:26 PM.

  2. #22
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    I am still none the wiser on if you A. sell them. B. How I can buy one from you.

    I will contact Ray.

    Thank you everyone for the useful input.

  3. #23
    Gimme a medal BenL's Avatar
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    Quote Originally Posted by Principia View Post
    I am still none the wiser on if you A. sell them. B. How I can buy one from you.

    I will contact Ray.

    Thank you everyone for the useful input.
    Umm post #19?

    I'd heed Iain's advice. It's limited for good reason.
    I don't want to get technical or anything, but alcohol IS a solution

  4. #24
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    I genuinely have no idea what his advice was. There is no doubt he might well be the most knowledgeable person on the planet when it comes to breathing air. Hence looking to him for a purchase.

    I can't be arsed with ploughin through all the twatwaffle to get to the end point, which will be that he just looses interest, the thread dies and I am not any further forward in my quest to make my little compressor a bit better and a bit safer.

  5. #25
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    Hi Iain,
    A couple of questions, as I have an MDE 45 (?) connected up to a little Coltri, which doesn't have a BPV). I understand what you are talking about with the flow direction - was pondering then, as a secondary should I reverse the standard direction? The flow would then come in through the smaller single opening in the spigot at the bottom, but... without a primary filter BPV, only a check valve then there is less of the surge that you describe surge perhaps?
    Maybe a spring required on the top of the element as well. Other thing is, in their normal filter flow, the do it MS then AC then Silica. I'm guessing in my limited understanding the silica will still try to dry the air that last little bit to help the AC? I do also have a coelescer before the second filter. Can you see any huge problems using the actual cartridge in reverse (although ideally I would find a repackable cartridge).

    Cheers
    Dave




    Quote Originally Posted by iain/hsm View Post

    By contrast I couldn't recommend a MDE BPR off the primary stack prior to the secondary because of the method of design and the opening pressure blast caused at the BPR opening pressure setting and pressure surge jet.

    Second the flow circuit for the MDE Series 40,50 models for portable compressors was designed for the older BS4001 air purity. Subsiquently for BS12021 you either have to up the BPR pressure setting and cause more pressure blast problems to the scondary filter chemical or you keep to the original BPR pressure setting and get less filter chemical life than you could.

    Third the opening "throat" of the small MDE filter chemical cartridges (ie the hole diameter of the plastic cartridge) introduces a "pressure jet" effect on the filter chemical this can and will a times disrupt the chemical stack, expand the contact area of the chemical matrix thus reduce the dwell time and lower the cartrige chemical life if you use it as a secondary filter stack

    Four, To answer the "back to front" aspect is that by following the engraved flow direction on the metal filter base this is for primary filtration where in order to extend the small chemical volume life expectancy you use the inside metal wall of the filter tower to act as a cooler to chill the gas and produce water condensate off the vapour dew point thus using the filter as both a separator and filter.

    To achieve this the dirty wet gas flows up ouside the plastic chemical cartridge then down the filter chemical to the outlet port side of the filter base.
    Now as to using it as a secondary filter stack your now "driving" the particulate dust out of the filter cartridge and out into you customers cylinders for one

    One of the very reasons why Bauer and others flow in the opposite direction, up through the filter chemical stack then out at the top and down the inside of the metal tower.
    Ive only just started lots more to come Iain
    Last edited by Dave1w; 25-11-2019 at 08:03 AM.

  6. #26
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    Post 16, option 2, but he's probably gone to bed by now

  7. #27
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    Quote Originally Posted by Principia View Post
    I genuinely have no idea what his advice was.
    I thought we had only just started explaining the considerations you require to make an informed choice

    Quote Originally Posted by Principia View Post
    no doubt he might well be the most knowledgeable person on the planet when it comes to breathing air.
    I'm probably not the most knowledgeable i just do a humble job of building stuff for others the best I can , but it was the best hope you were going to ever get of learning the pitfalls and considerations needed to make an informed choice.

    Quote Originally Posted by Principia View Post
    looking to him for a purchase.
    As explained direct sales are not allowed on this forum from commercial companies. I love this forum too much to jepodies that, I post in a private capacity and am not about to break an important forum rule I support. Than have the place taken over with crap from China and eBay sellers selling junk and keeping you guys in the dark about stuff.

    Quote Originally Posted by Principia View Post
    can't be arsed with ploughin through all the twatwaffle to get to the end point,
    Im not your personal shopper if you dont like it too bad. Try Twitter or Facebook your opinion is more important to them than it is to us.

    Quote Originally Posted by Principia View Post
    will be that he just looses interest,
    I doubt it, I have been in diving so long I dont know any other home

    Quote Originally Posted by Principia View Post
    thread dies
    They always do, But so will us all on a long enough timeframe

    Quote Originally Posted by Principia View Post
    I am not any further forward in my quest to make my little compressor a bit better and a bit safer.
    Well at least you now know not to call it a "Moisture Eye"
    And not to use the Nuvair 40% humidity card

    You now know the 10/20/30% humidity card is the indicator of choice after the secondary filter tower
    and the 20/40 60% is the indicator card post primary prior to the secondary
    You know now the need to fit a BPR after the visual indicator on the secondary
    and to fit a non return valve before the filter although we have not disscussed yet why.

    Sorry you cant be arsed with ploughin through all the twatwaffle to get to the end point
    Maybe for the best you try Twitter. Iain

  8. #28
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    Quote Originally Posted by Dave1w View Post
    Hi Iain,
    A couple of questions, as I have an MDE 45 (?) connected up to a little Coltri, which doesn't have a BPV). I understand what you are talking about with the flow direction - was pondering then, as a secondary should I reverse the standard direction? The flow would then come in through the smaller single opening in the spigot at the bottom, but... without a primary filter BPV, only a check valve then there is less of the surge that you describe surge perhaps?
    Maybe a spring required on the top of the element as well. Other thing is, in their normal filter flow, the do it MS then AC then Silica. I'm guessing in my limited understanding the silica will still try to dry the air that last little bit to help the AC? I do also have a coelescer before the second filter. Can you see any huge problems using the actual cartridge in reverse (although ideally I would find a repackable cartridge).

    Cheers
    Dave
    Dave

    Good point.

    Flow direction and the chemical component stack go hand in hand but I was warning of the additional risk of adding a secondary filter to an exisiting compressor
    using the MDE BPR and that the choice type brand of BPR is critical to avoid disrupting the chemical stack and for MikeF to explain why he made that MDE recommendation

    You also have additional considerations if you have or dont have a primary BPR off the compressor or a check valve before the secondary
    Each set up is different.

    But good point about flow direction you cant buy an MDE filter with a plastic throw away cartridge an just plumb it back to front due because of the chemical combination.

    The illustration below is the disruption pattern caused by fitting the MDE BPR pressure primary and the resultent opening blast on newly changed Series throw away cartridges disrupting flow is from top down. Note just assume that using the MDE plastic cartridge from bottom up you would just split the plastic cartridge.
    Hence why on most secondary filters the good ones are using the 316 stainless cartridge and making it repackable because of the cost.
    And why (I guess) even Bauer on the bigger P40 and P60 filter shells use aluminium throw away filter cartridges

    https://s730.photobucket.com/user/ia...b445c.jpg.html
    Last edited by iain/hsm; 25-11-2019 at 09:28 AM.

  9. #29
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    If one sticks to the manufacturers changing interval for the primary filter does this not negate the requirements for a secondary filter tower and a moisture eye? Or else why are they not equipping their compressors with them?

  10. #30
    Established TDF Member MikeF's Avatar
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    Iain

    OK I’ll bite. I didn’t recommend anything for ‘this application’ I have no idea how the OP intended to build his system and simply gave some suggestions as to where you can actually buy a filter tower PMV and visual moisture indicator. I also said that the MDE PMV is better than the the one SMP supplied me. It is. SMP supplied me one that works but is hard to set and has no plating and has a nice green patina these days. You can read more into it than that and make yourself feel better if you want.

    With regard to the pressure surge every day is a school day. can you explain what this is for the simple folk? Are you saying the MDE PMV has too high a flow when it opens and charges the filling whip? Or are you referring to a sudden increase of pressure / Flow into a second filter cartridge when a second tower is fitted post PMV and the PMV opens? I would have thought the PMV is the last component before the charging hose or am I being too simplistic?


 
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