The CST-DPLM boiler drum level measurement system provides continuous drum water level measurement based on differential pressure (DP). It is supplied as a complete package: a twin-chamber boiler balance container, a 3-valve manifold and a DP level transmitter with LCD display and 4–20 mA + HART output. The system delivers a stable, ±0.1 % accurate level signal for control-room display, automatic feedwater control and high/low level alarms and trips.
Designed to European standards (PED 2014/68/EU, EMC 2014/30/EU) for fire-tube and water-tube boilers, the balance container is rated up to 160 barg and 400 °C. ISE supplies the complete package and assists with installation and range calculation from your drum drawings.
What does the boiler drum level system include?
- Twin-chamber balance container: maintains a stable condensate reference column with temperature compensation, installed in parallel with the variable column that follows drum level.
- 3-valve manifold: HP isolating valve, LP isolating valve and centre equalising valve – zero check, isolation and transmitter removal without shutting down the boiler.
- CST305X-DPT differential pressure transmitter: microprocessor-based, local LCD, 4–20 mA + HART output, ±0.1 % accuracy.
All three components are supplied as a matched set, simplifying selection, purchasing and installation and avoiding errors from combining parts from different sources.
Principle of DP drum level measurement
The system uses the hydrostatic balance (wet-leg) method: a fixed condensate reference column in the balance container is compared with a variable column that follows the actual water level in the drum. The pressure difference between the two columns is proportional to level and is converted to 4–20 mA by the DP transmitter. The twin-chamber design eliminates errors caused by uneven condensation and temperature changes – a common source of error in simple wet-leg arrangements.
Advantages of the CST-DPLM boiler drum level system
- Continuous measurement with ±0.1 % full-scale accuracy and a stable signal for feedwater control loops.
- Reference-column temperature compensation reduces error during load and pressure changes.
- Maintenance without boiler shutdown thanks to the 3-valve manifold.
- 4–20 mA + HART, 12–24 VDC two-wire – connects directly to PLC, DCS or boiler controllers.
- Balance container rated to 160 barg and 400 °C, DN20 flanges at 400 mm centres.
- Optional SIL2 transmitter (IEC 61508 / IEC 61511) for safety interlocks, and ATEX versions.
- SS304 construction (SS316/316L optional); insulation and trace heating available.
Applications
- Continuous drum level measurement on fire-tube and water-tube boilers with control-room display.
- Automatic boiler feedwater control (feed pumps, feed valves).
- High-high / low-low level alarms and boiler trip interlocks.
- Power-plant and industrial boilers in food, textile, paper, wood, chemical and biomass applications.
- Replacement for, or addition to, gauge glasses and magnetic level gauges where remote monitoring is required.
Technical specifications
Balance container
| Parameter | Value |
|---|---|
| Type | Twin-chamber (double-wall) condensing balance vessel |
| Wetted material | SS304 (SS316/316L optional) |
| Process connection | DN20 flanges on both ports (EN 1092-1) |
| Flange centre distance | 400 mm standard (other sizes on request) |
| Design pressure | Up to 160 barg |
| Design temperature | Up to 400 °C |
CST305X-DPT DP transmitter
| Parameter | Value |
|---|---|
| Range | −4 to +4 kPa (adjustable within range) |
| Output | 4–20 mA + HART |
| Display | Integrated LCD |
| Power supply | 12–24 VDC, two-wire |
| Accuracy | ±0.1 % of span |
| Ambient temperature | −20 °C to +80 °C |
| Ingress protection | IP56 |
| Wetted materials | Stainless steel; Hastelloy / tantalum optional |
3-valve manifold
| Parameter | Value |
|---|---|
| Configuration | HP block, LP block, centre equalising valve |
| Body material | Forged stainless steel (carbon steel optional) |
| Pressure rating | Matched to balance container design pressure |
| Operation | Handwheel, packed stem |
Applicable standards
| Standard | Scope |
|---|---|
| PED 2014/68/EU | Pressure equipment – balance container, manifold |
| EN 12952 (parts 7 & 11) | Water-tube boilers – level indication and limiting devices |
| EN 1092-1 | Circular flanges – DN20 connections |
| EN 10204 | Material certificates (3.1 / 3.2 on request) |
| EMC 2014/30/EU | Electromagnetic compatibility |
| LVD 2014/35/EU | Low voltage – DC supply circuits |
| ATEX 2014/34/EU | Hazardous areas (certified versions on order) |
| IEC 61508 / IEC 61511 | Functional safety – SIL2 option |
| RoHS 2011/65/EU | Restriction of hazardous substances |
Certificates and conformity assessment are confirmed with the manufacturer for each order.
FAQ
Why does DP drum level measurement need a balance container?
Uneven condensation and temperature changes in the reference leg make the reference column fluctuate and cause measurement errors. The balance container keeps the condensate reference column full and stable, so the level signal is accurate and reliable.
Can it replace the gauge glass or magnetic level gauge?
The CST-DPLM is for continuous measurement and automatic control. Boiler safety rules still call for local indication such as the CST-MLG magnetic level gauge installed alongside the DP system.
What information is needed for a quotation?
Boiler operating pressure and temperature, centre distance between drum tappings, normal/high/low water levels, power supply and control system (PLC, DCS).
Related products
- CST305X-DPT differential pressure transmitter
- 3-valve manifold
- Boiler TDS blowdown control
- Magnetic level gauge
Where to buy the CST-DPLM boiler drum level system?
EQUIPMENT INDUSTRIAL SOLUTION CO., LTD (ISE) – Ho Chi Minh City, Vietnam – supplies genuine the CST-DPLM boiler drum level system with technical consulting, fast quotation and on-site commissioning support across Vietnam and Southeast Asia.
Contact us: Sales +84 909 617 185 – Technical +84 979 117 185 – Email: [email protected]
