The KROHNE DK37 M8 is a heavy-duty variable area (VA) flowmeter engineered for critical low-flow applications. By pairing a rugged all-metal design with modern electronic signal outputs, this metal tube purgemeter delivers exceptional reliability in process analysis, dosing systems, and chemical injection skids. Available as either a purely mechanical indicator or with a digital 4-20 mA/HART® transmitter for remote DCS integration, the DK37 M8 maintains high precision under extreme process conditions—withstanding pressures up to 220 barg (3190 psig) and temperatures up to +200°C (+392°F).
In analytical systems, flow stability directly impacts measurement accuracy. The DK37 M8 excels in sample flow monitoring for process gas analyzers. Its integrated needle valve enables micro-metering and high-precision flow adjustment. For installations experiencing fluctuating inlet or outlet pressures, the meter can be factory-fitted with internal differential pressure regulators to ensure a constant flow rate. To establish complete pipeline pressure diagnostics at the skid inlet, instrumentation engineers frequently pair the DK37 with a Rosemount 3051S Pressure Transmitter.
Designed for safety-critical environments, the DK37 M8 is fully SIL 2 certified (per IEC 61508) and approved for use in Safety Instrumented Systems (SIS). With global hazardous area approvals including ATEX, IECEx, and QPS, it operates safely in explosive atmospheres. For ultra-low flow applications where a cost-effective, purely mechanical indicator is preferred, the rugged KROHNE DK32/34 series provides an excellent alternative.
| Feature | Specification Detail |
|---|---|
| Measurement Principle | Variable area float (Metal tube rotameter) |
| Application Type | Low-flow monitoring for Liquids and Gases |
| Accuracy (Standard) | ±2.5% of measured value (per VDI/VDE 3513-2) |
| Accuracy (Optional) | ±2.0% of full-scale value |
| Repeatability | Less than 0.25% |
| Turndown Ratio | 10:1 |
| Flow Ranges (Water) | 1.6 l/h to 250 l/h (0.4 to 67 GPH) |
| Flow Ranges (Air) | 16 l/h to 8,000 l/h (0.6 to 300 SCFH) |
| Feature | Specification Detail |
|---|---|
| Maximum Process Pressure | 220 barg / 3190 psig (Higher ratings on request) |
| Process Temperature | -40°C to +200°C (-40°F to +392°F) |
| Ambient Temperature | -40°C to +70°C (-40°F to +158°F) |
| Inlet/Outlet Straight Runs | 0D Upstream / 0D Downstream (No straight pipe required) |
| Valve Configuration | Integrated needle valve for fine flow control |
| Flow Regulation | Optional inlet or outlet differential pressure regulators |
| Component | Available Materials |
|---|---|
| Measuring Tube | 316L Stainless Steel, Alloy C4, Alloy 400, Titanium (Grade 2), Alloy C276, Alloy 625 |
| Float & Internals | Matched to wetted parts; Ceramic or Ruby options for micro-flows |
| Surface Passivation | Optional SilcoNert®2000 (For trace gas analysis & moisture sensitivity) |
| Indicator Housing | PPS (Standard); 316L Stainless Steel (Optional for offshore environments) |
| Gaskets | PTFE, FFKM, FPM (Application specific) |
| Type | Specification Detail |
|---|---|
| Threads / Flanges | G1/4, 1/4 NPT, 1/2 NPT (Female); EN Flanges (DN15-25), ASME (1/2\" - 1\") |
| Tube Fittings | Swagelok, Ermeto, Gyrolok, Serto compression fittings |
| Indicator Type | Mechanical pointer (DK37 M8M) or Electronic Bargraph (DK37 M8E) |
| Outputs & Diagnostics | 2-wire 4-20 mA, HART® 7, NAMUR NE 107 diagnostics, up to 2 limit switches |
| Safety Approvals | SIL 2 Certified (IEC 61508); ATEX, IECEx, cQPSus, NEPSI, CRN, NACE compliant |
Q: Can the DK37 M8 cope with fluctuating process pressures?
A: Yes. The KROHNE DK37 M8 can be fitted with internal differential pressure regulators. These mechanical components compensate for variations in either inlet or outlet pressures, ensuring the configured flow rate remains highly stable for precise analyzer sampling.
Q: What is the primary benefit of the SilcoNert®2000 coating?
A: SilcoNert®2000 is an advanced surface passivation layer. In trace gas analysis (like detecting ppm levels of H2S or moisture), raw stainless steel surfaces can adsorb these molecules, distorting downstream readings. This coating creates a chemically inert barrier, ensuring the sample composition remains unaltered.
Q: Is the DK37 M8 suitable for high-pressure hydrogen service?
A: Absolutely. Built with a full metal tube design and offering heavy-duty pressure boundaries (up to 220 barg / 3190 psig), the meter is ideal for high-pressure hydrogen skids and chemical injection environments.
