What Is a Hydroscope?

Water level gauge is also called "level gauge" or "level gauge". Because the water in the boiler vaporizes and heats at high temperatures, the water and steam loss is large. It is necessary to constantly replenish the water to keep the water level in the boiler to a certain height. If the water level is too low, the boiler may explode. In order to know the water level in the boiler at any time, a water level gauge is installed on the boiler, and the water level gauge and the boiler form a communication device. Commonly used are glass level gauges, pressure level gauges, buoy level gauges, capacitance level gauges and resistance level gauges. Isotope level gauges can also be used at high temperatures and pressures.

Chinese name: Water level gauge
Foreign name: Water Gauge

Measuring range: 300 ~ 2200mm
Operating temperature: -20 ~ 450
Working pressure: PN0 ~ 6.4MPa

Water level gauge introduction

Instruments that automatically measure and record water levels in rivers, lakes and irrigation channels. According to the sensor principle, it is divided into float type, tracking type, pressure type and reflection type. Water level recording methods mainly include: description of recording paper, data display or type recording, perforated paper tape, magnetic tape and solid circuit storage, etc. The accuracy of the water level gauge is generally within 1 to 3 cm. The recording period of the water level gauge made in China includes 1 day, 30 days, and 90 days. Travel time error, mechanical clock is 2 minutes / day, quartz crystal clock is less than 5 minutes / month.

Water level gauge classification

Float type water level gauge

The principle is the rise and fall of the water level induced by the float. Ordinary water level gauges that directly make the float drive record structure in a mechanical way. There are telex and digital water level gauges that convert the amount of rotation provided by the floats into incremental electrical pulses or binary coded pulses for long-distance transmission. Digital sensing water level meter composed of reed switch. The more widely used is the mechanical water level gauge. The application of the float-type water level gauge requires logging equipment, which is only suitable for low-sand-content river sections where the bank slope is stable and the riverbed has little erosion and sedimentation. Logging is shown in Figure 1.

Optical Fiber Water Level Gauge

The optical fiber water level meter includes a water level sensor part and a control circuit terminal part. Among them, the water level gauge sensor part uses optical path coupling adjustment equipment to connect with the optical cable to transmit the optical signal carrying the water level information. The control circuit terminal part uses laser modulation technology to send modulated laser signals with different functions. The water level is obtained through modulation, comparison and detection Accurate information. This principle realizes the whole process of optical measurement, and does not use any charged devices outdoors, which can prevent static hazards and prevent lightning strikes.

Water level tracking type water level gauge

It is also known as a contact water level gauge. The electric stylus on the weight is used to contact the water surface to send out an electrical signal to make the motor rotate forward or reverse. The position of the water surface point is tracked at any time to measure the water level. Generally, an iron pipe is set up on a steep bank slope, and a suspension hammer and a suspension cable are raised and lowered in the pipeline to drive a recording or signal device. Iron pipe water inlets need to be provided with sand and still water facilities.

Water level gauge pressure type water level gauge

Its working principle is to measure water pressure and estimate water level. Its characteristic is that there is no need to build a static water log, the sensor can be fixed at the bottom of the river, and the pressure can be eliminated by using an impulse pipe to directly measure the water level. There are two types of pressure gauges. One type is a bubble type, which continuously delivers gas in the impulse tube, and uses an automatically adjusted pressure balance to convert the water pressure into a mechanical angle of rotation, thereby driving the recording mechanism. The other is an electrical measurement type, which uses a solid-state piezoresistive device as a sensor, which can directly convert water pressure into a voltage modulus or frequency output, which is transmitted to the shore for processing and recording with a wire (Figure 2).

Acoustic water level gauge

It is a type of reflective water level gauge, which uses the principle of sound waves to reflect from different interfaces to determine the water level. Divided into two types of air-mediated and water-mediated. The air-borne type uses air as the propagation medium of sound waves. The transducer is placed above the water surface, and the sound waves are reflected from the water surface. The water level can be calculated and displayed according to the echo time. The instrument does not touch the water body and completely gets rid of the adverse factors such as sediment, velocity impact and waterweed in the water. In the water-based type, the transducer is installed at the bottom of the river and emits sound waves to the water surface. Acoustic waves propagate in water media at high speeds and large distances, and no logging is required. Both water level gauges can be transmitted to indoor display or storage records using cables (see Water Level Observation).

Water level gauge difference

There are many kinds of water level gauge products. Among them, glass tube level gauges and glass plate level gauges are most used. Glass tube level gauges are divided into ordinary glass tube level gauges and quartz glass tube level gauges due to different materials. There is a difference between the two.

GZS-A two-color quartz glass tube level gauge

1) Measurement range: 300 ~ 2200mm

2) Working temperature: -20 ~ 450

3) Working pressure: PN0 ~ 6.4MPa

4), quartz tube test pressure: 13MPa

5), the body material: high-quality carbon steel or 1Cr18Ni9Ti

6), green when there is liquid, red when there is no liquid

GZS-C ordinary glass tube level gauge

It is suitable for use in various environments under normal temperature and pressure. The biggest feature is the low price and direct reading display.

Electro-hydraulic level gauges are widely used in rivers, ambers, reservoirs, channels, and hydropower stations.

Water Level Gauge Features

There are four commonly used water level gauges: glass tube type, flat type, two-color water level gauge and low status water level gauge.

First, glass tube water level gauge

Glass tube water level gauge, the nominal pressure generally does not exceed 1.6MPa, the nominal diameter of DN15 and DN20 two, the inner diameter of the glass tube should not be less than 8mm, the thickness is not less than 3mm.

The glass tube type water level gauge is mainly composed of a steam cock, a water cock, a glass tube, a sewage cock and a connecting flange.

The level and change of the water level in the boiler are displayed through the glass tube. The center line of the glass tube should be concentric with the center line of the water level gauge steam and water cock to prevent the glass tube from being broken by twisting stress. In order to prevent the blasting of the glass tube from hurting people, marbles are equipped in the water level gauge with steel balls. The steam and water blasting force makes the marbles automatically close the steam and water cocks. A protective cover should also be installed. The protective cover is generally made of a thicker temperature-resistant tempered glass plate. If the protective cover is made of iron sheet, there should be a gap of 12 ~ 15mm in width on the front and back cover walls in the direction of observing the water level, and its length should be larger than the length of the glass tube. The gap is left behind to allow light to enter for easy observation. Do not use ordinary glass as a protective cover, to prevent the glass tube from rupturing, but increase the danger.

Two-sided glass plate water level gauge

Double-sided glass plate water level gauge is mainly composed of steam valve, water valve, pressure plate, glass plate, sewage valve, sewage pipe and flange. Its characteristic is to replace the glass tube with a flat glass plate. The inner surface of the glass plate is usually provided with a triangular groove. The refraction of light in the groove makes the vapor-water boundary very obvious. Due to the different refractive indices of steam and water, steam and water will show different colors. Steam is bright white, and water appears dark. The boundary between the two is very clear and easy to observe.

When the working pressure of the boiler is high, a mica sheet can be lined behind the glass plate to improve the operational safety and extend the service life.

Three-color water level gauge

There are several types of two-color water level gauges, including transmissive, reflective and transflective.

1. Transmissive two-color water level gauge This water level gauge is composed of reflectors, light sources, red and green filters, cylindrical condensers, flat mirrors, screens, frames, soda cocks and other components.

The working principle of the transmissive two-color water level gauge is basically the same as that of other forms of water level gauges. The difference is that the light from the light source is reflected by a reflector and passes through the optical system to make the part of the light passing through the water appear green on the screen mirror. The part of the light passing through the steam is red on the screen mirror, which shows the change in the water level of the water-green and steam-red pots on the screen mirror.

2. Reflective two-color water level gauge The reflective two-color water level gauge uses light to have different refractive indices in water and steam, and makes the steam part of the water level gauge red through the reflection effect of the prism. The water part is green.

3. The structure of the transflective two-color water level gauge is between the transmission type and the reflection type, and its water level display uses both the transmission of light and the principle of reflection of light. The green light source device is on the tongue surface of the meter. The red light source device is on the left side of the meter, and there is also a color plate. After the light is transmitted and reflected, the water part of the water level meter is green and the steam part is red.

Fourth, low status water level gauge

According to the regulations, when the water level gauge is higher than 6m from the operating surface, a low-level water level gauge should be installed.

There are two types of low-level water level gauges: liquid column differential pressure low-level water level gauges and mechanical low-level water level gauges.

The liquid column differential pressure type low position water level gauge is made by measuring the static pressure difference between two liquid columns using the principle of hydrostatic pressure. According to the difference in the specific gravity of the liquid in the low-level water level indicator, there is a heavy-liquid low-level water level gauge with a specific gravity greater than 1, and a light-liquid low-level water level gauge with a specific gravity less than 1. There are also differential pressure type low-level water level meters.

The working fluid requirements for low-level water level gauges are as follows:

1. Insoluble in water.

2. It can be dyed into bright colors, which can form a clear dividing line with water.

3. It has a high boiling point and has no corrosion effect.

4. The viscosity should be as small as possible.

The heavy liquid that can meet the above requirements is carbon tetrachloride ( = 1623kg / m3). Trichloromethane ( = 1489kg / m3. Tribromomethane ( = 2890 kg / m3), or other mixtures prepared by other solutions. The density of commonly used heavy liquid is 1600 2000 kg / m3. In order to facilitate the observation of water level, you can add solubility Dyes: If 0.01% croton red is added, heavy liquids can be made bright red. Light liquids can generally be mixed with motor oil, kerosene and gasoline in different proportions. Adding an appropriate amount of phenolphthalein can make the light liquids appear red. The commonly used light liquid density is 700 ~ 800 kg / m3.