Within the Red Hat certification program, the RHCA is considered the most complete (and grueling) certification among the seven major Red Hat certifications. In fact, some equate the prestige of the RHCA to that of the Microsoft Certified Master and possibly the CCIE.
A plumbing fixture like a sink can not function properly without a sink vent. When a drain pipe drains it creates a negative pressure in the sink drain; the negative pressure will pull the water out of the p-trap of the sink that's draining and sewer gases can enter your home if a sink vent is not installed.
Bilge Blowers are the most important ventilation system source for boats with gasoline engine spaces or rooms. They should also be used in diesel engine rooms or spaces. Dangerous fumes can accumulate in the bilge, creating a situation ripe for a fire or explosion.