What should be considered when choosing a water level gauge for a fire pond

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This post was last edited by Sammy_Wang on 2016-3-30 20:08. Water level monitors for fire ponds; gauges for the water level in fire ponds and fire tanks. There are also level controllers and oil level controllers, which come in various types such as differential pressure type, static pressure type, ultrasonic type, and magnetic flap type. It is applicable to various types of tanks, wells, water containers, fuel tanks, pipelines, etc., such as rooftop water tanks in high-rise buildings, storage tanks, water treatment plants, sewage treatment plants, oil tanks, reservoirs, water towers, and more. When used in conjunction with a digital display, it enables remote telemetry of the dynamic liquid level over long distances (typically 4 kilometers), with the value displayed digitally. The digital display unit also has audio and visual alarm functions. Users can adjust the upper and lower liquid level values according to their needs. An automatic alarm is triggered when the measured liquid level reaches the upper or lower limit values ； It can also use the built-in relay device to automatically control the start and stop of water pumps and oil pumps. The 4-20mA continuous signal output by the transmitter can also be used in conjunction with variable-frequency speed control motors. The liquid to be tested can be water, oil, acid, alkali, and salt solutions; it is suitable for complex liquids with high viscosity or high temperatures. Working principle of the water level controller. The water level gauge for fire suppression tanks (essential for fire safety inspections) is used to maintain a certain water pressure; in the past, fire suppression tanks (tanks, reservoirs, water towers) were generally placed in the highest locations such as rooftops. As a result, operators had to first go to the site to check the water level, and then go to the control room to adjust the water supply or stop it, which was very inconvenient. For industrial water tanks, machine room sewage tanks, etc., it is often necessary to assign dedicated personnel to monitor them due to a simple water level issue. A level indicator consists of a transmitter, an air guide cable, a display, etc., while an intelligent level controller is made up of both the level indicator and the level transmitter. The level display instruments consist of intelligent digital displays as well as single and double gauge column digital displays, while the level transmitters include ordinary types, high-temperature types, oil-resistant types, ultrasonic types, and corrosion-resistant types. These devices enable real-time, intuitive digital and gauge column display of the level of the medium being measured. It can also keep the liquid level within the desired range, allowing for real-time display, alarm, and control of the liquid level in open or sealed containers or underground tanks from the instrument control room. The medium being measured can be water, oil, acids, bases, industrial wastewater, various high-temperature fluids, viscous fluids, and other conductive and non-conductive liquids. It can eliminate the effect of false liquid level caused by liquid fluctuations. It can be widely used for industrial remote control in industries such as water supply, oil refining, chemicals, food processing, pharmaceuticals, paper manufacturing, and sewage treatment. The level gauges for fire water tanks and reservoirs utilize integrated circuits, and are designed with consideration for the staged elevation of water levels in upper and lower tanks (water towers, reservoirs) in high-rise buildings. They offer functions such as combined control of upper and lower tanks, tank drainage, and water shortage protection. They can automatically replenish water into the reservoirs and drain excess water, effectively preventing overfilling due to too high water levels or damage caused by the pumps running idle. This is a product suitable for both industrial and domestic use. An ideal water tower-well supply system for urban and rural areas, schools, industrial and mining enterprises, as well as households – it is widely used in industries such as printing and dyeing, chemicals, food, beverages, brewing, and sugar production. It is an upgraded version of the traditional float-type water level gauge. According to Article 4.2.2, Clause 4 of the provisional version of the Standards for Inspection and Evaluation of the Installation Quality of Building Fire Protection Facilities (DB37/242—2008), the water level in the fire water tank should be displayable in the fire control room; and according to Article 4.2.3, Clause 9, the water level in the fire extinguishing tank should also be displayable in the fire control room. This standard came into force in July 2008. In the past, people did not pay much attention to this; they would often make their own buoys and use glass tubes to display the readings. Some use floating balls and magnetic flip plates, but they have the disadvantages of being prone to rusting and having a low cost-performance ratio. In some facilities, level indicators for fire water tanks and elevated fire water reservoirs are not installed in actual use. Some, fearing that the water replenishment system might get out of control, keep it in manual mode or turn it off; as a result, no level indicators are installed in the fire control room for these tanks, which means that the water level cannot be monitored. When the water level drops, neither automatic alarms nor automatic water replenishment occur, and it is even difficult to detect severe water shortages in time. In such cases, the fire suppression system becomes useless, with consequences that are unimaginable. Ensuring that fire ponds and elevated fire water tanks remain at their full water levels, as well as enabling remote monitoring from the fire control room, have become extremely important aspects of fire management. Failing to install level indicators for fire water tanks and elevated fire water reservoirs in the fire control room may also result in the risk of failure in the inspection, evaluation, and acceptance of the quality of the building’s fire protection systems. This product can be installed and set up without the need for professionals; its plug-and-play installation method is simple and convenient. The maximum distance between the level sensor (probe) and the display instrument is 4000 meters, enabling remote control and display. It features real-time digital display, with a measurement accuracy of up to the centimeter level. It also provides output for upper and lower limit alarm settings, as well as a 4-20mA current output. It is an upgraded version of traditional float-type and electrode-type level gauges. I. Overview: This product’s level sensor incorporates Japan’s advanced triple-seal technology to prevent leaks. The key raw materials, chips, and components are all imported, while the display and control unit uses PLC algorithms along with sophisticated signal reception and processing technologies. It is widely used for real-time measurement and control of water levels in tanks, reservoirs, water towers, wells, and other water storage structures across various industries. II. Principle: The level sensor operates on the principle that the static pressure of the liquid being measured is proportional to its height. It uses advanced isolated diffused silicon sensors to convert this static pressure into electrical signals; after temperature compensation and linear correction, these signals are transformed into standard electrical signals (such as 4–20 mA). A display controller is used to enable real-time monitoring and control of the liquid level on-site. II. Main technical parameters of the level gauges for fire ponds and fire water tanks: Measurement range: 0–100 m. Measured media: ordinary water, oil, acids, alkalis, sewage, viscous fluids, etc.; temperature of the measured media: 0–400°C. Output signal: 4—20mA. Display precision: 0.5%. Power supply: (220VAC, 24VDC). Output switch contacts: Upper, upper limit (normally open, normally closed). Upper limit (normally open, normally closed). Lower limit (normally open, normally closed). Lower, upper limits (normally open, normally closed). Transmitter installation methods: submersible, threaded, top-mounted (ultrasonic type). Display table size: 160×80 ； 96×96 ； 72×72 ； 48×96 ； 96×48 ； 48×48 ； 80×160. Table display format: digital display, single-bar digital display, dual-bar digital display. III. Installation and use of water level gauges in fire ponds and fire water tanks; Transmitter installation methods: submersible, threaded, and top-mounted (ultrasonic type). If the transmitter for the fire water tank is of the submersible type, flanges, wave-proof pipes, and weights can be installed during installation depending on the water level; if the water level is low and stable, these components may not be necessary. When the water temperature in the fire water tank is above 60 degrees Celsius, threaded installation can be used. During installation, a tee and valve can be added to the bottom side of the tank, after which the transmitter can be screwed in – the transmitter’s external thread size is M20*1.5. If an ultrasonic type of transmitter is used, a bracket or an opening in the tank cover of size M66*2 is required. Once the installation is complete, connect the positive and negative terminals of the transmitter to the corresponding positive and negative terminals of the display unit, set the range as well as the upper and lower limits, and it can then be put into normal use. In accordance with the requirements of the new consumer regulations, fire ponds or fire water tanks must be equipped with a level indicator (also known as a water level transmitter). Such an indicator consists of a detection sensor, a specialized signal cable, and a signal acquisition and display unit. A water level indicator consists of a display unit and a water level transmitter (also known as a water level gauge). The signal acquisition display is installed in the fire control center or control room to facilitate intuitive monitoring of water levels. The level transmitters consist of standard types, ultrasonic types, high-temperature and high-pressure types, oil-resistant types, sanitary types, anti-clogging and anti-sticking types, organic solvent-resistant type level transmitters, as well as corrosion-resistant types; they enable real-time digital and optical indication of the liquid level of the medium being measured. It can also keep the liquid levels of liquids, water, and organic solvents within the desired ranges. It enables real-time display, monitoring, alarm, and control of the liquid levels in open or sealed containers, underground tanks, and buried storage tanks from locations such as control rooms, offices, duty rooms, and fire control centers. The medium to be tested can be water, industrial wastewater, sulfate-based acidic or alkaline solutions, oils, organic solvents, fiber slurries, various high-temperature media, viscous media, and other conductive and non-conductive liquids. It can be widely used for monitoring industrial liquid levels, water levels, and organic solvent levels in industries such as water supply, fire protection, oil refining, light industry, mining, chemicals, coal, shipping, boilers, food processing, power generation, pharmaceuticals, paper manufacturing, and wastewater treatment. Key technical specifications of the water level indicator:
Display method: Energy-saving, high-brightness LED digital display, or high-brightness single/dual gauge column analog display ranging from 0 to 100%.
Alarm settings: Users can arbitrarily set alarm values within the measurement range.
Control settings: Users can arbitrarily set control values within the measurement range.
Service life: The average service life under normal use is 10 years.
Power consumption: Less than or equal to 5W.
Storage temperature: –40 to +100°C.
Materials to be measured: Industrial water, oils, acids, alkalis, salts, organic solvents, wastewater, viscous fluids, and other pastes and liquids.
Medium temperature: –35 to 400°C.
Measurement range: 0–0.3 to 100 meters (the minimum range can be 0.1 meters, and the maximum range can be 100 meters; the range can be selected or specified).
Environmental humidity: 0–100% RH.
Measurement accuracy: 0.5% FS.
Response sensitivity: 0.01 seconds.
Stability: Long-term operational stability exceeds 0.1% FS.
Power supply: 220VAC (24VDC is also available; 220VAC is the default).
Impact of power supply variations: Less than ±0.0005%/V of the output range.
Input signals: 4–20mA, 0–5V, etc. (4–20mA signal is the default).
Output signals: Relay, 4–20mA.
Operating temperature: –30 to +85°C (the temperature at which the device operates).
Material of the diaphragm: 316L stainless steel, Hastelloy, polytetrafluoroethylene (PTFE), etc.
Protection rating: IP68 for the sensor; IP65 for the main unit.
Power supply for the main unit: The main unit has its own 24VDC regulated power supply, providing a constant DC power source for the sensor.
Installation methods for the main unit: Wall-mounted (type 1拖8), cabinet-mounted (type 1拖1).
Impact of vibration: When vibrating at 200 Hz in any direction, the resulting error is 0.05%/g of the maximum range (this value is negligible).

Water level alarm for flood control towers:
● Stable performance, capable of operating around the clock with a long service life.
● Intuitive display.
● Easy installation, with a user-friendly menu for simple adjustment.
● Settings are stored in non-volatile memory (data is not lost even when power is cut off).
● Very long signal transmission distance of up to 5 kilometers (distance from the sensor to the display).
● Multiple sensor options available (resistant to corrosion, suitable for high temperatures, crystallization, scaling, applications with stirring, viscous fluids, volatile liquid pastes).
● Fully open menu; all control points can be adjusted freely and continuously. Values such as 0.6 meters, 2.5 meters, 8.5 meters, 11 meters can be used, but users can also set any values they desire, such as 0.35 meters, 1.99 meters, 8.25 meters, 9.56 meters, etc. (adjustments can be made freely and continuously).
The on/off status of each control point can also be set freely. For example, if the device should be turned on at 0.45 meters, select the “on” option; otherwise, select “off”. The same applies to all other control points.

Installation and usage of the water level indicator:
Installation methods for the transmitter: Submersible, threaded, top-mounted (ultrasonic type). If the transmitter for the fire water tank is of the submersible type, flanges, wave-damping pipes, and weights can be installed during installation depending on the water level; if the water level is low and stable, these components may not be necessary. When the temperature of the water in the fire tank is above 60 degrees Celsius, threaded installation can be used. During installation, a tee and valve can be added to the bottom side of the tank, after which the transmitter can be screwed in. The external thread of the transmitter is M20*1.5. If an ultrasonic type transmitter is used, a bracket or an opening in the tank cover with a M66*2 thread is required. After all these installations are complete, the positive and negative terminals of the transmitter should be connected to the corresponding terminals of the display device, and the range as well as the upper and lower limits should be set, after which the transmitter can be put into normal use. There are also similar products to those mentioned above, such as level controllers, water level indicators, fire tank water level alarms, fire tower water level alarms, high-level alarms, high-temperature resistant level transmitters, corrosion-resistant level transmitters, negative pressure transmitters, vacuum pressure transmitters, vacuum absolute pressure transmitters, level controllers, organic solvent level gauges, level transmitters, differential pressure level meters, organic solvent flow meters, static pressure level sensors, submersible level gauges, and other industrial control products. Feel free to ask for more information. Performance features: The water level automatic controller of this product utilizes state-of-the-art contactless control technology, and is processed by a fully digital microcomputer. As a result, it offers superior and more stable performance, higher sensitivity, a longer service life, and a lower failure rate. It features unattended fully automatic control, which effectively saves labor, reduces electricity consumption, and minimizes water waste. It is an ideal water supply and drainage device. It is widely applicable to the control of motors for deep well pumps, submersible pumps, centrifugal pumps, long-shaft pumps, etc. The water level control method allows for automatic control of the water level using various types of water level controllers, depending on the user’s and project’s requirements. I. Product Overview: The water level sensor is developed using advanced X-type diffused silicon pressure sensor chips from the American company MOTOROLA. It incorporates two world-leading technologies: precision silicon etching and silicon wafer lamination, making it a high-quality, cost-effective static pressure water level sensor. It is widely applicable to water level measurement and control in industries such as chemicals, metallurgy, environmental protection, food processing, water resources, urban water supply, municipal drainage, domestic water tanks, and fire water tanks. During installation, simply place the sensor at the bottom of the water, connect the amplification converter to the display and control panel, set the upper and lower limits, and the water level can be automatically controlled. The common specifications are 5 meters, 10 meters, 20 meters, and 100 meters.
II. Main technical parameters:
Range: 0–50 kPa, 0–100 kPa, 0–200 kPa, 0–700 kPa
Output: 4–20 mA DC
Operating temperature range: –25–80°C
Accuracy: ±0.2% of the range
Sensitivity: 1.2 (mV/kPa)
Overpressure tolerance: 2 times the range limit
Linearity: ±0.1% of the range

III. Product features:
1. High precision, high stability, and good cost-performance ratio.
2. Contactless, spark-free, and without moving parts, ensuring safety and reliability.
3. Special-treated air ducts that are flexible and resistant to stretching.
4. Made of high-quality stainless steel, offering durability and resistance to aging.
5. Can be directly placed in water, making installation simple.
6. The connection cables can be extended up to 4000 meters to the control room, facilitating use.

IV. Design principle:
When the water level sensor is placed at a certain depth in the liquid being measured, the pressure acting on the sensor’s surface in contact with the liquid is given by:
P = ρ·g·H + P0
Where:
P: Pressure acting on the sensor’s surface in contact with the liquid, in Pa
ρ: Density of the liquid being measured, in kg/m³
g: Local gravitational acceleration, in m/s²
P0: Atmospheric pressure at the surface of the liquid, in Pa
H: Depth of the sensor in the liquid or the height from its installation position to the liquid surface, in meters

The atmospheric pressure P0 at the liquid surface is introduced into the sensor’s backpressure chamber through the air ducts, thereby canceling out P0 on the sensor’s surface. This allows the sensor to measure the pressure as P = ρ·g·H. By measuring this pressure P, it is possible to determine the water level depth H. The pressure signal detected by the sensor is converted and amplified by electronic circuits, and then output as a standard 4–20 mA or 0–10 V signal to display controllers, recorders, frequency converters, etc. Water tank level gauges (by phone), level controllers, oil level controllers – these can be classified into several categories such as differential pressure type, static pressure type, ultrasonic type, and magnetic flap type. It is applicable to various types of tanks, wells, water containers, fuel tanks, pipelines, etc., such as rooftop water tanks in high-rise buildings, storage tanks, water treatment plants, sewage treatment plants, oil tanks, reservoirs, water towers, and more. When used in conjunction with a digital display, it enables remote telemetry of the dynamic liquid level over long distances (typically 4 kilometers), with the value displayed digitally. The digital display unit also has audio and visual alarm functions. Users can adjust the upper and lower liquid level values according to their needs. An automatic alarm is triggered when the measured liquid level reaches the upper or lower limit values ； It can also use the built-in relay device to automatically control the start and stop of water pumps and oil pumps. The 4-20mA continuous signal output by the transmitter can also be used in conjunction with variable-frequency speed control motors. The liquid to be tested can be water, oil, acid, alkali, and salt solutions; it is suitable for complex liquids with high viscosity or high temperatures. Working principle of the water level controller. The water level gauge for fire protection tanks (essential for fire safety inspections) is used to maintain a certain water pressure; in the past, fire protection tanks (pools, water towers) were generally placed in the highest locations such as on rooftops. As a result, operators had to first go to the site to check the water level, and then go to the control room to adjust the water supply or stop it, which was very inconvenient. For industrial water tanks, machine room sewage tanks, etc., it is often necessary to assign dedicated personnel to monitor them due to a simple water level issue. A level indicator consists of a transmitter, an air guide cable, a display, etc., while an intelligent level controller is made up of a level indicator and a level transmitter. The level display instruments include intelligent digital displays as well as single and dual-gauge digital displays. The level transmitters come in ordinary types, high-temperature types, oil-resistant types, ultrasonic types, and corrosion-resistant types, enabling real-time, intuitive digital and gauge-based display of the level of the medium being measured. It can also keep the liquid level within the desired range, allowing for real-time display, alarm, and control of the liquid level in open or closed containers or underground tanks from the control room. The medium being measured can be water, oil, acids, alkalis, industrial wastewater, various high-temperature fluids, viscous fluids, and other conductive or non-conductive liquids. It can eliminate the effect of false liquid level caused by liquid fluctuations. It can be widely used for industrial remote control in industries such as water supply, oil refining, chemicals, food processing, pharmaceuticals, paper manufacturing, and sewage treatment. The liquid level controllers for water tanks include those for fire suppression tanks, as well as controllers for general water tanks. Each of these controllers consists of a liquid level sensor and a display unit. The liquid level sensor is made up of a stainless steel probe and a rubber air conduit cable, while the controller itself comprises a display screen, setting buttons, and output contacts for controlling the upper and lower limits of the liquid level. The tank being monitored must be connected to the atmosphere; if the medium is corrosive or operates at high temperatures, an appropriate probe can be used. During installation, simply lower the probe slowly into the tank until it reaches the bottom, fix the rubber air conduit cable in place, and then connect ordinary wires to the controller in the control room. Set the upper and lower limits on the controller and connect it to 220V mains power – that’s all there is to the installation process. Key technical parameters: Measurement range: 0–100 m. Media that can be measured: ordinary water, oil, acids, alkalis, sewage, viscous fluids, etc. Temperature range of the measured medium: 0–400°C. Output signal: 4—20mA. Display precision: 0.5%. Power supply: (220VAC, 24VDC). Output switch contacts: Upper, upper limit (normally open, normally closed). Upper limit (normally open, normally closed). Lower limit (normally open, normally closed). Lower, upper limits (normally open, normally closed). Transmitter installation methods: submersible, threaded, top-mounted (ultrasonic type). Display table size: 160×80 ； 96×96 ； 72×72 ； 48×96 ； 96×48 ； 48×48 ； 80×160. Table display format: digital display, single-bar digital display, dual-bar digital display. Installation and use; Transmitter installation methods: submersion type, threaded type, top-mounted type (ultrasonic type). If the transmitter for the fire water tank is of the submersible type, flanges, wave-proof pipes, and weights can be installed during installation depending on the water level; if the water level is low and stable, these components may not be necessary. When the water temperature in the fire water tank is above 60 degrees Celsius, threaded installation can be used. During installation, a tee and valve can be added to the bottom side of the tank, after which the transmitter can be screwed in – the transmitter’s external thread size is M20*1.5. If an ultrasonic type of transmitter is used, a bracket or an opening in the tank cover of size M66*2 is required. Once the installation is complete, connect the positive and negative terminals of the transmitter to the corresponding positive and negative terminals of the display unit, set the range as well as the upper and lower limits, and it can then be put into normal use.