EMCO Restriction Orifice Plate – Type IRB. EMCO restriction plates are used to restrict the flow in order to prevent damage on pipe line equipment on the upstream side in blow down systems or to limit the flow / pressure to avoid damage on equipment on the downstream side. For insertion between compact flanges or clamp connection, we can help you with the right technical advice. Type IRB/1 is for RF flanges and type IRB/4 is for RTJ flanges.