Features (RKG-10 petroleum manholes assemblies): 1) Equipped on the top of tank truck 2) Entrance of fluid transfer operation inspection and maintaining the inside tank 3) Can protect the tank when involving in an emergency 4) Under normal practice, vent is closed when loading and offloading and temperature variation, it will cause the pressure variation inside the tank, such as air pressure and negative vacuum pressure, the vent of manhole cover will be closed automatically in order to keep the tank under a normal pressure 5) When involving in emergency, such as a car accident, the emergency exhaust valve will open the inside tank, meet the setting, in order to prevent explosion 6) Materials: a) Cover: aluminum b) Weld ring: aluminum c) Gasket: buna-N 7) Replacement parts: a) Key 1: vent b) Key 2: emergency exhaust valve 8) Technical specifications: a) Setting pressure of vent discharge: 7.14kPa b) Discharging capacity: ≥42.48m3 per hour when the pressure inside tank meets 0.021MPa c) Setting pressure of vent fo breathe: 2.54kPa d) Breathing capacity: ≥131.67m3 per hour when vacuum inside thank meets 7kPa e) Setting pressure of emergency exhaust valve: 0.0266MPa± 0.001MPa f) Pressure resistance: 0.254MPa g) Weight: 14.0kg/pc Outer packing: Carton dimensions: 48 x 45.5 x 23cm G.W.: 15.2kg Features (SYWG series delivery elbow): 1) Designed for those deep tank burial applications and a high flow rate due to the unrestricted flow pattern 2) Fits 4" top seal adaptors 3) Can also be ordered with a variety of different adaptors to meet any requirements 4) Single four bolt flange design allows for easy replacement of adaptors over competitive threaded styles, and is designed for extremely easy on and off coupling due to aluminum bronze alloy locking cams 5) Light weight cast aluminum 6) 4" male NPT/BSP, male cam and groove 7) Fits all 4" top seal adaptors 8) Protective base shield 9) Includes sight glass which allows the operator to see whether or not product is flowing 10) Ordering specifications: a) Products: SYWG-504, 604, 704 b) Connection threads: 4" male cam and groove, 4" male-NPT thread, 4" male-BSPT thread Outer packing: Carton N.W.: 5.80kg G.W.: 6.50kg