Terra glove boxes are designed as positive-pressure isolation chambers that operate with a continuous inflow of process gas and include bleed valves to relieve overpressures. Unless specified, they are not designed as low-leak or air-tight containment chambers, nor should they be used with hazardous substances that require air-tight seals. In containment applications, a glove box should typically be operated under continuous negative pressure, via a ventilated duct, so that any small leaks do not contaminate the operator or the environment.