Simple to build linear peristaltic vacuum
                        service air pump.

                       Parts shopping list.

                The first and most important part of this pump is the hose.

 This hose must be strong enough to hold its shape with vacuum inside yet be soft
and compliant to allow squeezing with the brayers.

                                          Parts list and sources.

 ( 1 ). The main hose:

    The original pump design used a two foot length of surgical tubing.  The smaller diameter
   stock will generally hold up with vacuum inside.
     Larger diameters must have proportionally thicker walls. Most larger diameter hoses will have
   relatively thinner walls and will have a tendency  to collapse and will not rebound under
   atmosphere pressure with vacuum inside.
     Hospital supplies that carry rubber surgical tubing should be available in or near most towns.
     Aquarium and fish stores now have silicone tubing to replace the older clear vinyl that tended
   to outgas plasticizer vapors into the fish tank.
     This tubing measures about 1/8Th of an inch inside and 5/16 th. of an inch outside diameter.
     I  purchased the hose from a dive shop. One can also try a sporting goods store.
     The hose is called "Sling material".  This kind is black in color and measures 3/16 th of an inch
   inside by 3/8 of an inch outside diameter.
      It was priced about a dollar per foot.
 This hose is from the dive shop.  The lighter colored hose is  
from the aquarium store.


 ( 2 ).  Thick short wide rubber bands.

            The short and wide colored rubber bands that are used to tie broccoli and other vegetables
          will work for use in forming the check valve, however it has been found that the rubber of
          these bands will not endure heavy repeated contact with the brayers.
            A suggested alternative to those are sections cut from discarded bicycle tire inner tubes.
            These may be found in the trash can of a bicycle repair shop or bike outfitter store.


 ( 3 ). Brayers.

           These can be purchased from an art supply store. There are several kinds of brayers for
          different ink bases. Avoid the older gelatin rollers for spreading oil based printing inks.
            I have found several kinds,  the hard solid clear plastic, the medium, soft solid rubber
          and a foam type. The medium 4 inch one is the least expensive and sells for $5.00 apiece.
               It is recommended that the end bearings of the brayer are greased before the heavier than
          normal use begins.


 ( 4 ). Stick of wood.

           The stick that I use in my version is called a "parting bead". This is the strip of wood that
          separates the upper outer and the lower inner window sash tracks in an older style window.
           This particular stock of wood measures 3/4 of an inch wide by 3/8 of an inch thick.
            A three foot ( a yard or meter ) long piece will do.
           This stock has pre rounded edges so one does not have to do any sanding.
           Any stick of appropriate dimensions will work, but one will have to sand the edges before
          assembly.  Lumber yards and building supplies offer a wide range of stock.


 ( 5 ). Duct or Gaffer's tape.

           Also available from a hardware store is a typical roll of two inch wide, general
          purpose utility tape.
           Others tapes like packing tape can be used if they can withstand
          repeated flexing and contact with the brayers.


 ( 6 ).  Silicone faucet grease. ( Optional pump sealant and lubricant )

          This is usually found in the plumbing section of a hardware store. It is normally
         applied  to the threads and packing gland around the stem of a faucet handle.
          According to the vender, silicone grease will not harm the rubber of the hose.
          Some small amount of this grease helps prevent the air from seeping through the
         brayer pinched hose.
  This lubricant was purchased in Dec.2000 in S.F. CA.
  This particular batch was a little on the 
runny side.

  I have added up my cost for building the pump.  Prices are very approximate as of Feb 2001
in San Francisco.  Actual prices of materials will vary depending on the time and location of the
 A question mark in the cost column means that I have gotten that item for free.
( 1 ). The main hose                                 $   2 
( 2 ). Thick short wide rubber bands               ? 
( 3 ). Two Brayers                                   $ 10 
( 4 ). Stick of wood                                  $   2 
( 5 ). Duct or Gaffer's tape                       $   3 
( 6 ).  Silicone faucet grease                      $   3 
( 1 )  Linear peristaltic air pump  around   $ 18 

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