Neither of these concepts are safe. The regulations refer to zoning of gas dangerous areas. The manifold would be considered zone 1 or 2.
The more onerous being zone 1 where gas is likely in normal operation. Zone 2 refers to gas being present only in a fault condition.
In both cases only certified electrical equipment is allowed to be installed in a gas dangerous area. The certification must refer to the gas in question.
The 110vac you refer to is definitely an ingnition source and should be either located in an Ex certified enclosure (refer IEC 60079), or outside the gas area.
This is risky and specialist stuff. If your installation causes an explosion you will be guilty under the Health and Safety Act.