| 摘要 |
<p>The metering assembly for supplying the chemical ingredients for making polyurethane foam is provided with two metering pumps which receive materials from the corresp. containers through anti-return valves. The materials pass to heaters and then to the spray gun, in proportions determined by piston rods which carry a stroke control device. This actuates a rapid-inversion switch working through distributor, provided with pneumatic valves for supply of air.</p> |
