Displacement servo gauge

A servo gauge is used on a tank containing a liquid. The gauge utilizes a displacer suspended on a support wire or tape which is wound on a storage wheel. The storage wheel is balanced by a counterweight. Any change in liquid level results in an imbalance which causes a servo motor to energize and rotate the wheel to bring the counterweight and displacer back into balance. The change in level is determined by counting the steps of motor operation. The changes in level are determined using the relationship between length and steps of motor operation. The level gauge is operable to continually correct calculation to compensate for changes in wire length per turn of the spool.

Numerous types of process instruments are available for measuring level, such as level in a tank. One such instrument is a displacement servo gauge. A servo gauge uses a counterweight or spring to balance the weight of a displacer. The displacer is suspended on a cable from a drum. The drum is coupled to the spring or counterweight. The spring or counterweight is selected so that an equilibrium condition exists when the displacer is at the top surface of the liquid. A change in the liquid level causes a corresponding change in the counterforce to move the gauge out of balance. Upon sensing such an imbalanced condition, a servo motor rotates the drum to raise or lower the displacer, as is necessary, until the gauge is again in balance. Rotational movement of the motor, which represents movement of the drum and thus the cable and displacer, is sensed to calculate the change in level.

Problems have been found associated with prior displacement servo gauges. Particularly, errors in level measurement can occur due to variations in drum diameter, as well as weight of the cable. Specifically, if the cable is wound in multilayers on the drum, then the exact length of cable relating to an increment of rotational movement of the servo motor shaft continually changes. This is due to the difference in circumferential length of the outer layers versus the inner layers when wound on the drum. Further, in the equilibrium state, the applied forces are balanced when the sum of the weight of the cable and the weight of the displacer is equal to the buoyancy force exerted by the liquid and the counterforce of the gauge. The weight of the displacer is a constant. In conventional gauges the counterforce weight is also constant. However, the weight of the tape varies with its extended length, which in turn varies with the liquid level. Thus, with conventional gauges, any change in weight of the tape requires a variation in the buoyancy by changing the penetration of the displacer and the liquid. This change results in an error in the reading of the level of the fluid, reflecting this change of penetration.

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Briefly float level gauge application scope and work instructions

Float liquid level gauge for scene: UFZ float level gauge to make a simple liquid level measuring instrument, is one of the medium level in atmospheric tank direct reading instrument, simple structure, visual direct and convenient installation and maintenance, etc; Main purpose and scope of application: applicable to petrochemical industry system in the corrosive medium of atmospheric storage tank, tank, oil fields, oil depot and other flat cone cover or arched container and general enterprise, civil building towers ( Water tank) The price is low level measurement, in order to solve the difficulty of the artificial measurement of liquid level.

Float liquid level gauge structure and principle, structure characteristics and working principle of the UFZ – Type 2 float type level gauge is designed according to the principle of force balance, its working principle. Set the weight of the float for W, float to F of buoyancy, a pointer to the weight of the heavy hammer G, the friction force of the whole system for F, when float float in a certain position in the liquid, the force to equilibrium state, W – both F – G± f=0。 When the liquid level changes, cause the change of float position, move through the wire rope drive pointer heavy hammer, the liquid level is shown on the scale ruler of corresponding position, achieve the goal of level measurement.

Float liquid level gauge work description: : float level gauge is liquid level meter in the working principle and design for a product of a simple structure, also is a kind of liquid level meter has long history. Float liquid level gauge because of its simple principle and structure, it is the result of measurement accuracy is relatively low, but with low price or in some of the requirements for accuracy is not high in the workplace have more applications.

Design principle of float liquid level gauge is the force balance principle in mechanics, the buoyancy provided by the gravity of the buoy and the liquid level, and the balance between the weight of the heavy hammer needle, to realize the liquid level height measurement and instructions. Float liquid level meter in the measurement is also affected by the friction between the internal components.

Float liquid level gauge measuring the liquid medium page rises, float by buoyancy F will increase, while the weight of the buoy W, the weight of the heavy hammer needle W1 friction force F are the same, and the system of force balance is broken, heavy hammer needle will decline in reducing buoy buoyancy of F, until to form a new equilibrium, such a heavy hammer the position of the needle can not only show the level value.

Float liquid level gauge of floating buoy at a particular level of weight W, when the liquid medium for buoy the buoyancy provided for F, float level gauge of heavy hammer pin for W1, float level gauge the friction between the parts for F, so that W should be with F, W1, equal to the sum of F, forming force balance.

Float liquid level gauge product features: float level gauge with its simple structure and low price, in some low accuracy measurement occasions you have more applications, such as petroleum and petrochemical system of oil tank, oil tank, and measurement of oil depots, and civil construction of the water tower or water tank level measurement, etc. Float liquid level gauge has certain corrosion protection function, can also be used in some low corrosive liquid medium measurement.

This article comes from kaidi edit released

Tank Terminal Automation System For Oil & Gas

Simplifying previously complex business processes

Three key challenges many tank terminals and refineries face are to reduce operating costs, ensure smooth IT processes and increase safety and security.

Tank Terminal Automation System is a powerful Terminal Management System that optimizes and automates all logistic and administrative processes in terminals and refineries. It equips you with all the tools needed to manage your plant in an efficient, transparent and safe manner.

How does Tank Terminal Automation System work?

Tank Terminal Automation System ensures rapid, transparent, secure and above all cost-beneficial processes. Its integration to various interfaces facilitates accurate and timely flow of critical data from the operational field equipment right up to the ERP system.

With the integrated and comprehensive quantity accounting you will have continuous access to current information about your product stocks as well as inputs and outputs. It doesn’t matter whether you store one or several different groups of products, whether you exclusively store your own products or whether you are a tank storage service provider. You will always be in control, able to monitor your processes and to react quickly and accurately.

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Advantages of the Magnetic Level Gauge

The magnetic level gauge is now widely used throughout process industries as an effective level control device (see our recent article on MLI technology and principle of operation for more information).

A magnetic level gauge is often used in applications where a sight glass (or glass sight gauge) is either ill-suited based on process variables or is underperforming based on plant requirements. These can include enhanced safety for personnel; environmentally risky situations including media leakage or fugitive emissions; need for maintenance reduction; or need for high visibility from a distance. Typical shortcomings of glass sight gauges include:

    • High pressures, extreme temperatures, deteriorating seals/rings/gaskets, and toxic or corrosive materials may cause a risk of fugitive emission of dangerous substances.
    • The glass in a sight glass can become quickly discolored, thus decreasing level visibility, or it can acquire microfractures, which can become a personnel safety issue if left undetected.
    • Liquid/liquid interfaces can be very difficult to read in a sight glass particularly if the liquids are of similar color. Clear liquids can also be difficult to see in a sight glass.
    • Liquids that tend to coat or build-up on surfaces can hinder visibility by forming an opaque film on the glass.
    • To cover a large measuring span, sight glass assemblies typically must be staggered using multiple sections.



The obvious safety benefit of the MLI over a sight glass is reduced chance of breakage. If the process fluid is under extreme pressure or temperature, the likelihood of sight glass breakage is increased. The pressure boundary of an MLI is made of robust metal, frequently the same as the vessel piping, making MLIs as safe as the surrounding piping system itself. The indicators, transmitters, and switches are all mounted externally and, therefore, are unaffected by toxicity, corrosiveness, or other process fluid characteristics.

Another safety benefit is that the chemical compatibility with the fluid in an MLI is restricted to only three components, the metallic chamber, gaskets and float. With glass sight gauges, the process fluid may have chemical compatibility issues with any of the wetted materials—glass, metal, or sealants.


MLIs are virtually maintenance free once installed because the indicator never touches the process fluid. With sight glasses, the gauges must be periodically checked for leaks and cleaned on a regular basis. Scaling, etching and build-up on the glass from the process fluid can cause the sight glass to become unreadable.


Visibility of the fluid level from long distances is another major reason for selecting an MLI over a sight glass gauge. Sight gauge level gauge are intended to be viewed at maximum distances of around 10 feet (3 meters). However, the bright contrasting colors of the flags or a fluorescent shuttle on an MLI permit visible level indication at distances up to 100 feet (30 meters) or greater. Newer, more advanced visual indicators, such as those from Orion Instruments®, have viewing ranges up to 200 ft. (60 m).

This article comes from magnetrol edit released

The working principle of servo gauge level transmitters

Servo gauge level transmitters are unique in that this level sensor uses the principle of displacement to measure level. Their high accuracy makes them very popular in custody transfer and inventory control. Endress+Hauser and Honeywell have most of this market tied up, but you can still find other companies competing. So let’s talk about how a servo gauge level transmitter works.

The device makes contact with the product using a displacer connected to a measured wire around a wire drum. It counts the rotations of the drum, then calculates the distance to the displacer when it touches the product’s surface. It detects the surface by monitoring the change in the displacer weight as it begins to float. The drive motor adjusts the displacer’s position as the level changes.

The wire drum works with a stepping motor, which comes in a few different flavours. Some vendors have patented products that use magnetic couplings between the drum and the motor. How these types of level sensor find their level can vary depending on vendor and technique, but the principle remains the same. As an added bonus, a servo gauge level transmitter can measure interface, spot, and profile densities.

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What does an automatic tank gauge do?

An Automatic Tank Gauge is a device that automatically measures the level of crude oil, LNG and petroleum products in storage tanks and raises an alarm when the level goes down or up the threshold limits. It operates electronically and keeping track of any leakages in the tank. When the upper limit of re-filling the tank is reached, it cuts off the supply from the inlet pipeline and intimates the operator on their human machine interface.

Automatic tank gauge systems measure the levels of liquids inside tanks with the help of electronic probes. These probes consist of long rods that house certain number of sensors known as floats. The position of the floats informs the operator sitting at the automatic tank gauge console about the amount of petroleum product present in the tank. Apart from measuring the petroleum levels, the probe rod also houses thermistors that measure the liquid temperature.

An automatic tank gauge console machine is connected electronically with all the storage tanks located inside the main facility and displays all the internal views of a storage tank to the operator sitting at the console.

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We manufactures Tank Level Indicators and Tank Level Gauges for many liquid level sensing and measurement applications. We offer precision electronic level sensors as well as mechanical indicators for applications that do not have power available.

Our mechanical Liquid level tape measure (LLTM series) provides a full to empty tank reading in inches via a tape measure. The Level keeper indicator (LKI series) is a multi point system which displays full to empty readings via bright LED lights. We also have a Continuous Level Monitor (CLM series) which is designed for accurate continuous level indication with accurate readings every 1/4″ of level movement.

The Ultrasonic Distance sensors are the most accurate and can be used in tanks up to 30 feet deep.

This article comes from liquidlevel edit released

How to Read a Heating Oil Tank Gauge for LPG LNG

In an oil-heated home, nothing is more important than making sure you don’t run out of heating oil. Even if you pay a premium for Automatic Heating Oil Delivery, it’s important to occasionally check your home heating oil tank to make sure you do not run out. In this post, we’ll walk through the nuances of reading a typical float-style heating oil tank gauge for LPG LNG and introduce some alternative ways of monitoring your fuel oil tank.

How to Read a Float Gauge in a Heating Oil Tank

Most fuel oil tanks come with a traditional float-style gauge. This fuel oil tank gauge for LPG LNG features an arm with a float attached to its end, and a hinge. There is a plastic vial with a disk that indicates how full the heating oil tank is. As the float lowers, so does this disk.

How Accurate is a Heating Oil Float Tank Gauge for LPG LNG?

Since these are not precision heating oil tank gauges for LPG LNG, they should only be used as an approximation of how full a tank is. Because of the moving parts inside, these can also be prone to wear over time. If you suspect your heating oil float gauge is stuck, simply unscrew the plastic vial by hand. Use your finger to press the disk down. If the gauge is not stuck, the disk should easily move down, then slowly float back up and remain up, indicating the arm is moving freely.

This article comes from fuelsnap edit released

Benefits of Automatic Tank Gauge

The Benefits of Automatic Tank Gauge With ongoing measurement of tank levels and temperature you can insure the integrity of your product while also preventing costly inve.

Automatic tank gauge (ATG) systems measure the levels of liquids inside tanks with the help of electronic probes. These probes consist of long rods that house certain number of sensors known as floats. The position of the floats informs the operator sitting at the ATG console about the amount of petroleum product present in the tank.

The Automatic Tank Gauge is engineered to provide the utmost in long, dependable, trouble free gauging. Censtar diesel tank level gauge can detect liquid level and temperature, automatic tank gauge systems has the advantages of both multi function and long life.

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Advantages Of Magnetostrictive Level Gauge

Magnetostrictive level gauge for high-precision cleaning requirements of the liquid level measurement, accuracy of 1mm, the latest product accuracy has been able to reach 0.1mm.

Can be applied to the boundary measurement between two different liquids. Magnetostrictive biggest advantage lies in the high resolution, can be done micron level. Explosion-proof intelligent electronic circuit design can calculate the volume

Magnetostrictive level gauge only movable parts for the float, maintenance is very low. Used in various types of storage tank level measurement environment adaptability and strong installation and other characteristics in short range measurement relative to the radar and other liquid level meter cost is very high, the function is also a lot.

The display has current, temperature, and interface display. This is the magnetostrictive level gauge can become today’s gas stations and other metering tank on the most commonly used one of the products.

This article comes from auto-instrument edit released