Foundry cores hardened by catalyst gas mixed with air - where analysers in gas recovery circuit prevent danger of an explosion

摘要

The parent patent describes the hardening of foundry moulds, esp. cores made of sand with a resin binder and hardened by a mixt. (ab) of a gas or vapour catalyst (a) in a carrier gas (b). The mixt. (ab) is fed through the core and then collected so cpd. (a) can be sepd. from the mixt., purified and re-used in a closed circuit. In this addn. gas (b) is air; the mixt. (ab) is drawn through the core by suction; and the concn. of cpd. (a) in the mixt. flowing through the circuit is continuously monitored and kept below a critical value (CCa) which could cause an explosion. The suction time is pref. longer than the gassing time to allow air only to be drawn through the core.