Description
Plastic Threaded Rotameter for Water – 500 to 5000 LPH
The Plastic Threaded Rotameter for Water, Range 500 to 5000 LPH is a reliable, economical, and easy-to-use variable-area flow meter designed for continuous visual monitoring of water flow in industrial, commercial, process, utility, and water-treatment applications. With a flow measurement range of 500 to 5000 Litres Per Hour (LPH), this model is suitable for applications requiring higher water-flow measurement while maintaining the simplicity and convenience of a mechanical rotameter.
Designed specifically for water with a specific gravity of 1, this plastic threaded rotameter combines a transparent polycarbonate body, durable SS 316L float, and ABS end construction to provide a practical solution for local flow indication. The instrument is supplied with 2 – inch BSP (M) threaded connections at both the top and bottom, allowing convenient inline installation in compatible piping systems.
The rotameter operates using the proven variable-area flow measurement principle. Water enters from the bottom of the instrument and flows upward through the measuring section. As the water flow changes, the SS 316L float moves vertically inside the transparent body. The position of the float corresponds to the flow rate indicated on the graduated scale.
With a specified accuracy of 2% of full scale, a maximum operating temperature of 60°C, and maximum operating pressure of 5 kg/cm², this rotameter provides an economical solution for general-purpose water-flow monitoring within its specified operating conditions.
Variable-Area Flow Measurement Principle
The Plastic Threaded Rotameter works on the variable-area principle, a simple and widely established method of measuring fluid flow.
Water enters through the bottom connection and moves upward through the measuring tube. The flow causes the float to rise until it reaches a stable position corresponding to the flow rate. When the flow decreases, the float moves downward.
The operator can observe the position of the float through the transparent polycarbonate body and read the corresponding value from the graduated scale.
This operating principle provides several practical advantages:
- Direct visual flow indication
- No external electrical power required
- Continuous flow monitoring
- Simple mechanical construction
- Easy operation
- Low maintenance requirements
- Quick visual inspection
- Economical installation
The simple construction makes the rotameter particularly useful where straightforward local flow indication is preferred over complex electronic instrumentation.
500 to 5000 LPH Flow Range
This model is designed for a water-flow range of:
500 to 5000 LPH
The relatively high flow range makes it suitable for larger water-flow applications compared with smaller low-flow rotameter models.
The graduated scale enables operators to observe flow conditions and determine whether the system is operating within the required range.
Typical applications may include:
- Water treatment plants
- RO and water purification systems
- Industrial cooling-water systems
- Filtration systems
- Process-water circulation
- Industrial machinery
- Utility-water lines
- Washing and cleaning systems
- Water circulation equipment
- Process equipment
- General industrial flow monitoring
The rotameter should be selected according to the actual application conditions and installed within the specified operating limits.
Polycarbonate Flow Body
The body of the rotameter is manufactured from polycarbonate, providing a transparent measuring section.
One of the major advantages of a transparent flow body is that it allows the operator to visually observe the movement and position of the float while the system is operating.
This can assist with:
- Confirming that flow is present
- Monitoring changes in flow
- Checking float movement
- Identifying unstable flow
- Detecting abnormal operating conditions
- Performing routine visual inspections
Polycarbonate construction also contributes to the instrument’s lightweight and economical design.
The instrument should always be operated within the specified maximum temperature and pressure limits.
SS 316L Float
The rotameter is equipped with an SS 316L float that acts as the primary moving measurement element.
The float responds to changes in the upward force produced by the flowing water. When the flow increases, the float rises; when the flow decreases, it falls.
SS 316L is commonly used in industrial instrumentation because of its corrosion-resistant properties and suitability for a variety of process environments.
The robust float construction supports reliable operation for compatible water applications.
2 – inch BSP (M) Connections
The instrument is provided with:
2 – inch BSP (M) threaded connections at top and bottom
These connections allow the rotameter to be installed inline with compatible piping systems.
The standard flow arrangement is:
Bottom Inlet → Measuring Section → Top Outlet
Correct orientation is essential because the float is designed to operate under the influence of gravity and upward fluid flow.
Before installation, users should verify that the existing piping arrangement and fittings are compatible with the 2 – inch BSP male connections.
Water Specific Gravity
The rotameter is specified for:
Water – Specific Gravity 1
The flow scale is intended for water having the specified density characteristics. If the instrument is used with another liquid having substantially different density or viscosity, the displayed flow value may not correspond directly to the water calibration.
For this reason, the instrument should be used for the intended water application unless suitable calibration or correction factors are available.
Operating Temperature
The maximum specified operating temperature is:
60°C
This rating makes the rotameter suitable for many ambient-temperature and moderately warm water applications.
The process temperature should be checked before installation. The maximum specified temperature should not be exceeded during operation.
Operating Pressure
The maximum specified operating pressure is:
5 kg/cm²
The rotameter should be installed in a system where the normal operating pressure remains within this limit.
Users should also consider possible pressure fluctuations and surges during system operation.
Appropriate piping support should be provided to prevent excessive mechanical loading on the rotameter and its threaded connections.
Accuracy
The specified accuracy is:
2% of Full Scale
This level of accuracy makes the rotameter suitable for many general-purpose industrial flow-monitoring applications.
It is particularly appropriate where operators need a dependable indication of whether the process flow is within the required operating range.
For applications requiring certified high-precision flow measurement, the instrument should be evaluated against the specific measurement requirements of the application.
Tamper-Proof Scale Sticker
The instrument is supplied with a tamper-proof scale sticker.
The scale provides the visual reference required to determine the flow rate based on the position of the float.
The scale graduation is specified as:
LPH / LPM
This provides convenient flow-rate indication for water-flow monitoring applications.
The operator should observe the float position consistently and interpret the reading according to the supplied calibration scale.
Compact Industrial Construction
The approximate dimensions of this model are:
400 mm Height × 120 mm Width
The larger measuring section is appropriate for the instrument’s higher 500–5000 LPH flow range.
Despite its larger capacity, the plastic construction provides a lightweight alternative to conventional metallic flow-meter assemblies.
Before installation, sufficient clearance should be provided around the instrument for proper visibility and maintenance.
Applications
1. Water Treatment
The rotameter can be installed on suitable water-treatment lines to monitor flow through filtration, treatment, or circulation equipment.
2. RO and Purification Systems
It can be used for local flow monitoring in compatible reverse-osmosis and water-purification equipment.
3. Cooling-Water Systems
Industrial equipment often requires continuous cooling-water circulation. This rotameter can provide local indication of flow in compatible cooling circuits.
4. Industrial Machinery
The instrument can be used to monitor water used for cooling, cleaning, processing, or other utility applications.
5. Filtration Systems
The visual indication provided by the rotameter can help operators verify water flow through compatible filtration equipment.
6. Process Equipment
The 500–5000 LPH range makes this model suitable for various process-water applications where a local flow indication is required.
7. Utility Water Lines
The instrument can be installed on suitable industrial utility-water lines to provide continuous local monitoring.
Key Features
- Plastic threaded rotameter
- Designed for water-flow measurement
- Flow range 500 to 5000 LPH
- Suitable for water, specific gravity 1
- 2% of full-scale accuracy
- Transparent polycarbonate body
- SS 316L float
- ABS end material
- 2 – inch BSP (M) connections
- Top and bottom threaded connections
- Bottom inlet and top outlet
- Inline installation
- Maximum operating temperature 60°C
- Maximum operating pressure 5 kg/cm²
- LPH/LPM scale graduation
- Tamper-proof scale sticker
- Approximate dimensions 400 H × 120 W mm
- Direct visual flow indication
- No external power required for mechanical indication
- Economical design
- Suitable for industrial water-flow monitoring
Why Choose This Plastic Threaded Rotameter?
The Plastic Threaded Rotameter 500–5000 LPH provides a simple and economical method of monitoring relatively higher water-flow rates without requiring complicated electrical instrumentation.
Its transparent polycarbonate body allows the operator to observe the SS 316L float directly, while the graduated scale provides an easy reference for determining the water-flow rate. The 2 – inch BSP (M) threaded connections provide a convenient installation arrangement for compatible piping systems.
The instrument is particularly suitable for applications where continuous local flow indication, simple operation, low maintenance, and economical instrumentation are important.
Its combination of a wide flow range, transparent construction, SS 316L float, plastic end components, and direct visual indication makes it a practical choice for a wide variety of water-flow monitoring requirements.
Installation Guidelines
For proper operation, the rotameter should be installed vertically, with the inlet at the bottom and outlet at the top.
Before commissioning, verify that:
- The piping is compatible with the 2 – inch BSP (M) connections.
- The instrument is installed vertically.
- Flow direction is bottom to top.
- Operating flow remains within 500–5000 LPH.
- Operating pressure does not exceed 5 kg/cm².
- Water temperature does not exceed 60°C.
- The piping is properly aligned and supported.
- The float can move freely inside the measuring section.
- The system is free from conditions that could cause excessive vibration or pressure surges.
- The flow is allowed to stabilize before taking a reading.
Maintenance
The rotameter’s simple mechanical construction allows straightforward routine inspection. Periodically check the transparent body, float movement, scale, threaded connections, and overall condition of the instrument.
If deposits or contaminants accumulate inside the measuring section and affect float movement, the instrument should be isolated from the process and cleaned using an appropriate method compatible with its construction materials.
Any maintenance activity should be performed only after the instrument has been safely isolated from the process pressure.
Conclusion
The Plastic Threaded Rotameter for Water, 500 to 5000 LPH is a practical and economical solution for continuous local water-flow monitoring. Its variable-area measurement principle, polycarbonate body, SS 316L float, ABS end construction, 2 – inch BSP (M) connections, and direct visual indication make it suitable for a wide range of industrial and utility applications.
With a 500–5000 LPH flow range, 2% full-scale accuracy, maximum operating temperature of 60°C, and maximum operating pressure of 5 kg/cm², this rotameter is well suited for compatible water-treatment, cooling, filtration, process, and utility systems.
For applications where a simple, visible, compact, low-maintenance, and economical water-flow measuring instrument is required, this Plastic Threaded Rotameter provides a practical and effective solution.
Japsin Instrumentation – Since 1974

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