Metering device

Abstract

Metering device for metering a readily combustible substance, in particular acrolein acetal, from a source or a container for the substance into a vacuum line ( 38 ) by a pump whose pump power is controllable, characterized in that the pump is driven a compressed air motor ( 28 ) operated displacement pump ( 26 ), and that between the positive displacement pump ( 26 ) and the vacuum line ( 38 ) a pressure holding and regulating valve is arranged whose dimensionless delivery height H/Ho[mWS/1 mWS] with the dimensionless delivery rate Q/Qo[m 3 /h/1 m 3 /h] according to the Formula: { H/Ho}={C 1*( Q/Qo )} 0.333 , where. H=Hydraulic pressure at the inlet of the pressure holding and regulating valve Ho=1 mWS C1=Constant for the pressure holding and regulating valve Q=Hydraulic flow rate Qo=1 m 3 /h.

1 . Metering device for metering a readily combustible substance, in particular acrolein acetal, from a source or a storage container for the substance into a vacuum line ( 38 ) by a pump whose pump power is controllable, characterized in that the pump by driven by a compressed air motor ( 28 ) operated displacement pump ( 26 ), and that between the positive displacement pump ( 26 ) and the vacuum line ( 38 ) a pressure holding and regulating valve is arranged whose dimensionless delivery height H/Ho [mWS/1 mWS] is related with the dimensionless delivery rate Q/Qo[m 3 /h/1 m 3 /h] according to the formula:
   { H/Ho}={C 1*( Q/Qo )} 0.333 , where.   Hydraulic pressure at the inlet of the pressure holding and regulating valve   Ho=1 mWS   C1=Constant for the pressure holding and regulating valve   Hydraulic flow rate   Qo=1 m 3 /h.   
     
     
         2 . Metering device according to  claim 1 , characterized in that the pressure holding and regulating valve ( 35 ) comprises: a cylindrical valve housing ( 1 ) with an upper side ( 2 ), in which a central inlet bore ( 3 ) is provided with a diameter d 1 , and with a bottom ( 4 ), in which an inner bore ( 5 ) is provided, whose diameter d 2  is greater than that of the diameter d 1  of the inlet bore ( 3 ) and which forms an outlet of the pressure holding and regulating valve, a closure piston ( 8 ) with an upper part ( 9 ), whose diameter d 3  is smaller than the diameter d 2  of the inner bore ( 5 ) and larger than the diameter d 1  of the inlet bore ( 3 ), a freely movable, circular sealing disc ( 7 ) made of an elastomer between the closure piston ( 8 ) and an inner sealing surface ( 6 ) which is formed between the inner bore ( 5 ) and the inlet bore ( 3 ) on an inner side of the valve housing ( 1 ), and by a compression spring ( 12 ), which is supported in the inner bore ( 5 ) and presses through the closure piston ( 8 ) the sealing disc ( 7 ) against the inner sealing surface ( 6 ). 
     
     
         3 . Metering device according to  claim 2 , characterized in that the sealing disc ( 7 ) has a diameter d 3  which is greater than the diameter d 1  of the inlet bore ( 3 ) plus the radial extent of the inner sealing surface ( 6 ), and which is smaller than the diameter d 3  of an upper part ( 9 ) of the closure piston ( 8 ). 
     
     
         4 . Metering device according to  claim 2 , characterized in that a gap ( 16 ) formed between the upper part ( 9 ) of the closure piston ( 8 ) and the inner bore ( 5 ) has a cross-sectional area corresponding to the cross-sectional area of the inlet bore ( 3 ).