Specifying a manway for a sanitary tank starts with one question: does the access point need to hold pressure, or does it need to let operators see inside? A sanitary tank manhole is not a single product—it is a family of designs built for very different duties. This guide compares two of the most common: the high pressure manhole and the whole glass tank manhole.
A high pressure manhole (usually a round or oval pressure manway) is engineered to stay sealed while the vessel is pressurized or under vacuum. EFUN’s sanitary high pressure round manhole uses a reinforced ring, a gasket rated for the design pressure, and a hinged or bolted cover that clamps the seal tighter as pressure rises. In CIP loops and carbonated or pressurized process lines, that seal integrity is what keeps cleaning cycles safe and leak-free.
Pressure rating depends on diameter, gasket material, and cover thickness. Always confirm the rating against your maximum operating and CIP pressure before specifying—EFUN can supply the test certificate on request.
A whole glass manhole replaces the solid cover with a full-diameter tempered-glass viewport. EFUN’s sanitary whole glass manhole lets operators inspect level, color, mixing, and foam without opening the tank or breaking the sterile boundary. The trade-off is pressure: the glass is rated for visual inspection at low or atmospheric pressure, not for the same pressure class as a steel cover.
| Factor | High Pressure Manhole | Whole Glass Manhole |
|---|---|---|
| Pressure rating | Rated for pressurized / vacuum service | Atmospheric / low pressure viewing |
| Visibility | Solid cover, no sight | Full-diameter see-through viewport |
| Access for cleaning | Opens fully for manual CIP access | Wipe-clean glass; separate manway for entry |
| Typical use | CIP tanks, pressurized / carbonated lines | Atmospheric tanks needing visual monitoring |
| Standards | 3A, DIN, SMS, ISO machined | Tempered hygienic glass, 3A finish |
If the tank is pressurized, vacuum-rated, or part of a CIP loop, the high pressure manhole is the default. If the priority is continuous visual monitoring at atmospheric pressure—and you can pair it with a separate pressure-rated access—a pressure manhole with sight glass can give you both a pressure-rated seal and a viewing window in one unit, reducing the number of tank penetrations.
Specify the right manway for your tank
Send EFUN your tank drawing and design pressure—our engineers will recommend a high pressure or whole glass manhole that matches your process and standards.
Standard whole glass manholes are rated for visual inspection at low or atmospheric pressure. For pressurized vessels, choose a pressure-rated manhole or a pressure manhole with an integrated sight glass.
Both use hygienic, crevice-free designs. High pressure manholes open fully for manual cleaning; whole glass versions add a wipe-clean viewport but should be checked for scratches that can harbor residue.
Often yes. A pressure manhole with sight glass combines a pressure-rated seal with a viewing window, which reduces the number of penetrations in the tank shell.
See inside without breaking the seal
Explore EFUN’s glass-view manways and sight-glass options for atmospheric and low-pressure tanks.
