The amount of foot-hole, is used to measure the level of the oil tank and the transfer of oil samples specialized accessories. Each set atop a tank, mostly located in the vicinity of the tank ladder platform. About metering orifice diameter of 150 mm, can be sealed with a lid and tension bolt holes, in order to prevent closed iron manhole covers and striking sparks in the manhole cover seal groove embedded oil pads or soft metal (copper or aluminum). Since the measuring tape in contact with the steel friction sparks export easily, so the inside of the bore tube lined with copper (or aluminum) sets or measurement points outside the fixed installation sparking nonferrous guide grooves (cast-foot tank) . In order to ensure the amount of oil along the same position each time ruler, to reduce measurement error, the amount of oil hole in the side wall provided with a guide groove aluminum or copper. Hole is on the bottom of the tank bottom shell welds should be welded where a measurement reference boards to reduce relative error of each measurement if necessary. Amount of hole sub-foot hole with a rotary volume mounted on top of the tank, the tank for measuring the oil level and temperature and sampling, etc., because of chemical materials all with varying degrees of noxious odors, can not be measured Emissions to the atmosphere. In order to complete the measurement procedure to ensure that the environment is not affected and operations workers to operate safe, environmentally friendly amount of hole can play a role in this regard. 2 foot hole quantity and size of DN LH 100 330 190 150 360 210 Note: DN150 DN100 specifications are the specifications foot pedal and manual rotary Second, the amount of maintenance hole hole regular gate , easy to damage and leaks occur, and therefore regularly identify its rigor. When the identification, at the edge of the hole with a thin coating of paint, gently cover the manhole cover, hand plus a certain force, such as the release liner has obvious signs of complete, it can be considered qualified. If traces of incomplete, indicating hole cover is not tight, replace the gasket.