Diptube Materials and Length

The materials of diptubes of sprayers can be LDPE and PP. Generally, the diptube is made of LDPE. However, because LDPE is soft, sometimes 1% to 3% of diptubes in one batch may curve severely during shipment, which lead to difficulty on auto-capping progress. Therefore, PP, which is hard, will be used to make diptubes to avoid such bending.

A problem of PP diptube is the PP diptube may pierce the plastic bag during the shipment because PP diptubes are too hard and just like thick needles. Therefore, it is advised not to pack PP diptube sprayers so crowded as LDPE diptube sprayers in the boxes. Of course, less packing amount per box will increase the shipment cost, especially for air freight.

The length strategies for LDPE and PP diptubes are different. A LDPE diptube is designed to reach the edge of the bottle bottom to suck as completed liquid as possibly. Situation of PP diptube is different. PP is hard, so if a PP diptube is forced to bend like a LDPE diptube, the bended PP diptube will generate a force pushing the cap out. It will cause inconvenience of capping progress. Therefore, normally, PP diptube is designed to reach the center of the bottle bottom vertically.

When buyer and seller communicate the diptube, the length of the diputbe must be specified. The type of diptube length must be clarified to avoid mistakes. There are three types of diptube length including Exposed length, Real length (or Gross length), and FBOG length. Exposed length refers to the part outside the housing. Real length refers to the part including the inside and outside the housing, which also means the gross length when the diputbe is taken off from the housing. FBOG length means the length from the based of gasket. FBOG length is similar to the height of the bottle and decided by only the bottle’s dimensions. Thus FBOG length will not change according to sprayers with different housing length. Overall, the following equations simply explain the relation between three lengths. a) Exposed length + the length inside housing (normally 5 to 6 mm) = Real length. b) Exposed length + the length of housing from gasket to end = FBOG length.


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