There are a wide variety of appliances out there for use with large diameter hose (LDH). And...those appliances can be outfitted with pressure gauges and relief valves in addition to the standard appliance control devices. When selecting a manifold or water "thief" style appliance, a relief valve is pretty important since the valves on this appliance will most likely be open and closed under pressure over the duration of the fire scene operation. The relief valve reduces the possibility of over-pressurizing the hose and therefore we recommend it be set at the service test pressure of the LDH supplying (or leaving) the appliance. A pressure gauge on an LDH manifold is a nice feature to have when trying to coordinate pump discharge pressure settings over complex hose layouts or when using the manifold at a tanker loading station. Finally, regardless of the type of LDH appliance used, fire departments need to ensure that each appliance is service tested annually during the department's hose testing program.