Polyurethane FoamIsocyanate by ebo15297


									Polyurethane Foam/Isocyanate

Isocyanate is one of the       There are various types
components in broadly all      of isocy-anate, but com-
foam products, such as         mon to all of them is that
foam mattresses, inner         they react to the humid-
liners in cars, cushioning     ity of the air, thus forming
in car seats, chairs, and      very hard crystals which
sofas. The hard qualities      wear the pumps and the
are used for insulation of     mechanical shaft seals, if
houses, machines, tubes,       any.
etc. As a matter of curios-
ity we can also mention
the green foam in which
flowers for decorations are

Tagholm 1
DK-9400 Nørresundby
Phone: + 45 96 32 81 11
Fax: + 45 98 17 54 99
Internet: www.desmi.com
E-mail: desmi@desmi.com
      There are different methods to avoid that the              phthalate) or mesamol under pressure be-
      humidity of the air gets into the storage tank:            tween the seals. The results have been very
                                                                 mixed, but the risk of running into problems
      •    The tank is provided with a sili-cagel filter         has been so big that it can only be recom-
           which absorbs the humidity from the air as            mended to implement these so-lutions if the
           the tank is emptied and air is sucked into the        customer himself takes the responsibility for
           tank, so that it is not flat-tened out.               the solution desired.

          Method of

      •    At the top of the storage tank a protecting       •   The only solution we can give our whole-
           layer of gas (nitrogen) is added. Similarly           hearted support is to use a MAGNETICALLY
           the tanker which brings the raw material,             COU-PLED pump.
           has got gas at the top of the tank. When
           filling the tank, the tanker pumps the liquid     •   Selecting bearings
           into the storage tank, the top of which is            Our first selection would be bronze bear-
           connected to the top of the tanker. In this           ings. Some isocyanates, however, contain
           way no air at all gets into the isocyanate,           additives which do not go well with bronze,
           and there is no exhalation into the environ-          so this solution must be rejected. The next
           ment.                                                 thing we can do, is to put carbon bearings
                                                                 into the pump. But, if there are crystals in
      •    Instead of using nitrogen ultra-dry air can           the isocyanate, carbon bearings will not be
           be used. There are air-dryers which totally           the solution. Therefore carbide bearings will
           remove the humidity.                                  be the only solution.

      •    Systems pumping isocyanate should be              •   Normally the viscosity varies from 10 to 200
           provided with a filter or a strainer so as to         cSt.
           avoid crystals, if any, to circulate the system
           constantly.                                       •   The first magnetically coupled pump for iso-
                                                                 cyanate was sold in June 1992. Since then it
      •    All isocyanates are hazardous, and the va-            has been running 24 hours a day, and up till
           pours should not be inhaled. Contact with             now it has not been opened.
           the skin gives discolora-tion of the skin, and
           prolonged contact may result in allergy reac-     •   Pump selections:
           tions.                                                ED…E-1U22 or
                                                                 ED…E-1U33 or
      •    Mechanical shaft seals                                -1U88.
           Through the ages all kinds of seals have
           been used, from soft shaft seals to double
           mechanical shaft seals with DOP (dioctyl-

Tagholm 1
DK-9400 Nørresundby
Phone: + 45 96 32 81 11
Fax: + 45 98 17 54 99
Internet: www.desmi.com
E-mail: desmi@desmi.com

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