RKG Series Top-Mounted Carbon Steel Safety Manhole Covers – Versatile Solutions for Liquid Transport

RKG Series Top-Mounted Safety Manhole Covers – Versatile Solutions for Liquid Transport

The RKG series manhole covers are essential top-mounted components for fuel tankers, chemical tank trailers, and hazardous material transport vehicles, combining loading/unloading access, ventilation, and emergency protection. These manhole covers provide convenient access for filling and emptying while ensuring tank safety during pressure fluctuations or unexpected incidents.

Equipped with a vacuum-pressure vent valve and an emergency relief valve, the vacuum-pressure vent valve remains closed under normal conditions to maintain tank integrity. During fuel loading, unloading, or temperature changes that cause internal pressure variations, the vent valve automatically opens to release or draw in air, keeping tank pressure within the safe range. In emergencies such as fire or accidental impact, the emergency relief valve opens rapidly to release excessive pressure, effectively preventing explosions or fuel leaks.

Global Terminology Variations
This top-mounted safety device is known by different names around the world. In Europe, for example:
Germany: “Tankdeckel mit Sicherheitsventil” or “Mannlochabdeckung für Tankfahrzeuge”
France: “Couvercle de trappe avec soupape de sécurité”
Italy: “Coperchio uomo con valvola di sicurezza”
Spain: “Tapa de registro con válvula de seguridad”
Netherlands: “Tankluik met veiligheidsklep”
United Kingdom: “Tank Truck Manhole Cover with Relief Valve”

In Asia and the Americas, it may be referred to as a “Tank Top Manhole Cover,” “Pressure-Vacuum Tank Lid,” or “Safety Vent Manhole Assembly.” Despite the varying names, the core function remains the same: safeguarding the tank and controlling pressure during liquid transport.

Key Features and Benefits
Durable Materials: Handles, cover plates, and clamp rings are made of galvanized carbon steel for excellent strength and longevity. Emergency relief valve covers are made of low-pressure aluminum alloy for lightweight and corrosion resistance.
Versatile Sealing Options: Available with Buna-N (Nitrile) or Viton (FKM) sealing rings to meet diverse chemical and environmental requirements.
Easy Installation: Clamp-tight design allows fast mounting and removal. Pre-installed manhole neck simplifies installation.
Enhanced Safety: Spring-loaded emergency relief valve opens automatically, complying with international tank truck standards (NTTC DOT406, GB18564.1), preventing tank explosions.
Leak Prevention: Pressure-vacuum relief valve provides automatic sealing to prevent hazardous fuel spills even in the case of rollover.
Dual-Level Safety: Safety lock ensures dual-stage operation for extra protection before the emergency valve fully opens.
Operational Convenience: 250mm (10-inch) emergency relief port allows easy insertion of loading pipes during top-loading operations.

Technical Specifications
Vent discharge setting pressure: 6–12 kPa
Vacuum opening pressure: -2 to -4 kPa
Emergency relief valve pressure: 21–32 kPa
Operating temperature range: -20°C to +50°C

Models and Configurations
16-inch Clamp Type Manhole: RKG-460TC series
16-inch Bolted Type Manhole: RKG-460TB series
20-inch Clamp Type Manhole: RKG-560TC series
20-inch Bolted Type Manhole: RKG-560TB series

These models cater to various tanker sizes and liquid transport requirements and can be customized to comply with international standards.

Applications
The RKG series manhole covers are widely used in fuel, chemical, water, and hazardous material transport. They provide a reliable safety and pressure control solution for tank trucks globally and are recognized by operators in Europe, Asia, and South America as essential components for secure top-mounted tank operations.