Level gauges

Fig. 14. OxyTech/Uhde HU-type cell a, cell bottom b, cathode c, anode d, cell cover e, bus bars f, brine level gauge g, brine flow meter h, bypass...

Level gauging has existed at least as long as written history markings on the walls of Egyptian temples show that as early as 3000 years ago humans tracked the level of water for hydrologic data. These nilometers are some of the first recorded uses of systems to measure level (1). 

Fig. 23. Nuclear radiation level gauge, using an Ohmart-type ceU stack.

Monomer emulsions are prepared in separate stainless steel preemulsification tanks, which are usually equipped with an agitator, manometer level gauge, cooling cods, temperature recorder, mpture disk, flame arrester, and various nozzles for charging the ingredients. Monomer emulsions maybe charged in one shot to the reactor or, more commonly, fed continuously throughout the polymerization. 

Figure 7 shows nozzle locations and support arrangements for a typical horizontal vessel (7). The saddles used for support are sustained by concrete pedestals or steel stmctures. Sufficient clearance between the bottom nozzles and the support saddles needs to be provided for access to the nozzle flange bolts. The manway can be located on the end head of the vessel, the topside of the vessel, or the side of the vessel. The preference is for an end manway wherever possible for accessibiHty, except when it is limited by the level gauges and controls that are commonly mounted off the heads. 

Fig. 1.4. Miniature boiler fittings mode from brass a water-level gauge, a steam valve, a pressure gauge, and a feed-water injector. Brass is so easy to machine that it is good for intricate ports like these.

Liquid level above seal pan in bottom of column. Poor stripping of bottoms product. High pressure drop across section. Board mounted instrument improperly calibrated. Level gauge in field not properly blown down or even checked. Operation problem. 

Gauges used for measuring the liquid level in vessels may be of semitransparent and even nontransparent materials. Figure 3.2 illustrates a simple level gauge on a steel vessel used for liquid ammonia storage. As shown, a narrow strip of insulation is taken away from the vessel s shell to expose the bare metal. Consequently, the heat transfer coefficient from the... 

Figure 3.2. Liquid-level gauge for an ammonia tank.

Figure 5.10.3, Vessels—level control on outlet. Legend FIC, flow indicator controller LG, level gauge LIC, level indicator controller LAWL, level alarm for water level, M, motor.

Provide reliable seal liquid makeup, using liquid level gauging and monitoring wth recording to ensure good records of performance. The liquid level must be maintained otherwise, the hazards of a bleedthrough or backflow can become serious. 

When a boiler may not be shut down for maintenance of the level control chambers isolating valves can be fitted between the water-level control and the steam space. In this instance, the valves must be capable of being locked in the open position and the key retained by a responsible person. When these valves are closed during maintenance periods the boiler must be under manual attendance. Fitting of these valves should only be with the agreement of the insurance company responsible for the boiler. Drains from the water-level controls and level gauges should be collected at a manifold or sealed tundish before running to the blowdown vessel. 

For instance, a level gauge in a tank with an alarm on it could warn an operator that unless something is done quickly, the tank may overflow. A spill not only wastes material, but could present a fire hazard as well as a hazard to the environment. A similar alarm system might also alert the operator that the tank is nearly empty. This may be important because a pump downstream may bum up if it continues to operate with no feed. 

Use electronic or mechanical level gauges, not glass sight glasses. 

Still-gauging methods are adequate for only the largest leaks. The accuracy of most tank-installed liquid level gauges is usually /s in. at best. A product loss reflected by a 0.062-in. level drop for a 100-ft-diameter tank translates to a 306 gal/day leak. If this Vi6-in. drop in product level is not discernible from the masking effects of fluid expansion, losses in excess of 2650 barrels annually will go undetected. At, for example, 20 per barrel, this loss amounts to over 53,000 for a single tank. Most importantly, the associated liability risks of groundwater contamination could involve much greater potential costs. 

Are containers equipped with an approved liquid level gauging device (except those filled by weight) ... 

Are containers fitted with a fixed tube liquid level gauge at 85% of water capacity ... 

Are all storage tanks fitted with liquid level gauges ... 

Are liquid level gauges adequately protected from physical damage ... 

GLAND MATERIAL LEVEL GAUGE (PLAN 52/53) TEMP INDICATOR (PLANS 21,22. 23,32, 41) HEAT EXCHANGER (PLAN 52/53) REMARKS... 

A343 Seal level gauge SEAL LG c 1 1 ryes (true) Or no ( Ise)... 

At least weekly, the liquid level gauges of low-pressure containers should be observed. If, at any time, a container shows a loss of more than 10%, it should be refilled, unless the minimum gas requirements are still provided. 

LEVEL SWITCHES/LEVEL GAUGE MFR/MOD. NO. PRESS. GAUGE/THERMOMETERS MFR/MOD.NO. 

Coalescer Head.Flanged/Quick Opening/Hinged/Davit Supports Saddles/Legs. Instruments By Purchaser/Vendors Diff. Press. Gauge, Level Gauge, Press. Gauge, Relief Valve, Temp. Indicator with Thermowell. 

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