An 18 inch non-vented threaded manway, for tanks that must stay sealed at the top
SII-34300013 is Snyder's 18 inch non-vented threaded tank manway, moulded in high density linear polyethylene. It weighs 3 lb and ships in a package 18 by 18 by 3 inches. Unlike a vented lid, it closes the 18 inch opening with no path for air. That is what you want when the tank breathes through a dedicated vent elsewhere, when vapour from the liquid has to go out through a vent line or a filter rather than out of the lid, or when the stored liquid must be kept away from outside air, dust and insects as completely as possible.
Vented or non-vented: not sure which you need? Call 866-418-1777 and tell us how the tank is filled and vented, or get freight to your ZIP and add it to your cart above.
The one rule with a sealed lid
A tank still has to breathe. Every gallon pumped in pushes out a gallon of air, and every gallon drawn out has to be replaced by air from somewhere. If you fit a non-vented lid, the tank must have another working vent, sized for the fastest fill or draw rate it will see. Without one, filling pressurizes the tank and can push liquid out of fittings, and draining pulls a vacuum that can draw the walls in. If you are not certain your tank has a separate vent, do not fit this lid until you have checked, or order the vented version instead.
With a separate vent in place, a sealed manway is the better choice in several situations: chemical storage where fumes must be routed away from the work area, water storage where the vent carries a screen or filter and the lid should not bypass it, and any tank where the top opening is only for occasional inspection and should otherwise stay shut.
It is also the lid to keep on the shelf when a tank's vent and fill arrangement has been reworked. If you have added a vent fitting and a fill line elsewhere on the tank, a vented lid on top becomes a second, unfiltered opening; swapping it for a sealed one closes that gap.
What to check before you buy
- The opening. This manway is 18 inch. Measure the threaded opening on the tank.
- The thread. Threads are not standard between makers. Give us the tank make and part number and we will confirm with Snyder that SII-34300013 fits it.
- The vent. Confirm the tank has another vent before you install a sealed lid.
- The liquid. High density linear polyethylene handles water, most fertilizers and many common chemicals. Check anything else in our chemical compatibility guide.
Shipping and installing
At 3 lb in an 18 by 18 by 3 inch package, it is a small shipment. The listed price is before freight; the freight cost estimator gives the cost to your ZIP. To install, clean the threads on the tank opening, start the lid by hand, and turn it down snug without a tool. Then open the tank's other vent, confirm it is clear, and only then start filling.
Ready to order? Add it to your cart at the top of this page, get LTL freight to your ZIP, or call 866-418-1777. The listed price is before freight.
Freight
LTL freight is quoted to your ZIP with the freight cost estimator or by phone at 866-418-1777. The listed price is before freight.
See this tank
Product video. Watch the 18" Non-Vented Threaded Tank Manway video (55 seconds) with dimensions, fittings and shipping notes.
Ready to order?
Add it to your cart at the top of this page, get LTL freight to your ZIP, or call 866-418-1777. The listed price is before freight.
