Krohne vs Endress+Hauser Chemical Feed & Storage Equipment: Comparison & Best Fit

INTRODUCTION

In municipal and industrial water treatment, the “set it and forget it” mentality regarding chemical feed systems is a primary driver of operational inefficiency and compliance violations. While metering pumps and storage tanks are the muscles of the system, the instrumentation—specifically flow meters and level transmitters—acts as the nervous system. A surprising industry statistic suggests that up to 30% of chemical dosing costs are wasted due to overdosing caused by sensor drift, poor turndown ratios, or incorrect material specification. For engineers specifying plant upgrades or greenfield projects, the choice often narrows to two European giants: Krohne and Endress+Hauser (E+H).

This article provides a rigorous technical analysis of Krohne vs Endress+Hauser Chemical Feed & Storage Equipment: Comparison & Best Fit, focusing on the instrumentation that monitors and controls these critical process loops. These technologies are deployed in harsh environments, ranging from ferric chloride storage to sodium hypochlorite dosing and polymer injection. The consequences of poor selection in this category are severe: run-dry pump failures, chemical spills, inaccurate billing, and regulatory fines for disinfection byproducts or discharge violations.

Design engineers and plant directors must look beyond brand loyalty and evaluate these manufacturers based on electrode noise rejection, liner permeability, diagnostic capabilities, and lifecycle support. This guide dissects the engineering nuances required to select the right tool for the specific chemical application, ensuring process stability and cost containment.

HOW TO SELECT / SPECIFY

Selecting instrumentation for chemical feed and storage is fundamentally different from specifying general process water meters. The fluids are non-Newtonian, corrosive, conductive, or prone to off-gassing. Below are the engineering criteria essential for navigating the Krohne vs Endress+Hauser Chemical Feed & Storage Equipment: Comparison & Best Fit landscape.

Duty Conditions & Operating Envelope

The operating envelope for chemical feed is characterized by low flow rates and high turndown requirements. Unlike raw water intake lines, chemical feed lines often operate at velocities below 1 ft/s, which challenges the accuracy of standard electromagnetic flow meters. Engineers must verify the low-flow cutoff points and accuracy curves at the bottom 10% of the range.

Pressure surges from positive displacement metering pumps (diaphragm or peristaltic) create pulsating flows. The selected flow meter must have a high sampling frequency and advanced signal processing to average these pulsations without creating “noisy” output that destabilizes the PID control loop. For storage applications, temperature fluctuations significantly affect ultrasonic signal speed; therefore, integrated temperature compensation is mandatory.

Materials & Compatibility

Chemical compatibility is the single most common failure mode. Standard EPDM or NBR liners used in water applications will fail within weeks in Sodium Hypochlorite or Sulfuric Acid service.

• Liners: PTFE (Teflon) and PFA are industry standards for aggressive chemicals. However, for vacuum service (which can occur during tank unloading or pump suction conditions), PFA must be reinforced (often with a wire mesh or robust bonding) to prevent liner collapse.
• Electrodes: Hastelloy C is a baseline, but Tantalum, Platinum, or Titanium may be required for specific oxidizers. Krohne is noted for its ceramic measuring tubes in certain product lines, which eliminate the liner entirely, offering superior dimensional stability under temperature and pressure cycling.

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• Permeability: Chlorine gas and other small-molecule chemicals can permeate standard PTFE liners over time, corroding the coils behind the liner. High-density/virgin PTFE or ceramic designs are critical countermeasures.

Hydraulics & Process Performance

In chemical feed skids, straight pipe runs are a luxury often unavailable due to space constraints. Engineers must evaluate the upstream and downstream straight-run requirements (expressed in Pipe Diameters, e.g., 5D/3D). Both Krohne and E+H offer “0D” or reduced-run models, but the physics behind how they achieve accuracy differs. Understanding the trade-off between installation footprint and measurement uncertainty is vital.

For Coriolis mass flow meters (often used for polymer or high-value chemicals), pressure drop becomes a critical design parameter. High-viscosity neat polymer can cause significant head loss through the bent tubes of a Coriolis meter. The specification must define the maximum allowable pressure drop at peak viscosity.

Installation Environment & Constructability

Chemical rooms are often classified as hazardous environments or, at a minimum, corrosive atmospheres. Plastic (polycarbonate) transmitter housings may degrade when exposed to UV or chemical fumes over decades. Aluminum or Stainless Steel housings (NEMA 4X/IP67 or IP68) are preferred.

Constructability note: Chemical feed lines are typically small bore (0.5″ to 2″). The weight of the flow meter relative to the PVC or CPVC piping is a structural concern. Adequate pipe support immediately adjacent to the meter flanges is required to prevent stress fractures in the plastic piping.

Reliability, Redundancy & Failure Modes

A primary failure mode in magmeters for chemical service is electrode coating. Non-conductive coatings (like grease or polymer buildup) insulate the signal, while conductive coatings can short the signal. Advanced diagnostics that monitor electrode impedance are necessary to trigger maintenance alarms before measurement is lost.

For level measurement in storage tanks, redundancy is best achieved by using dissimilar technologies. For example, a non-contact Radar level transmitter serves as the primary continuous measurement, while high-high and low-low mechanical float switches or vibrating forks provide hard-wired interlocks for spill prevention and pump protection.

Controls & Automation Interfaces

Modern chemical feed systems are moving away from simple 4-20mA analog signals toward digital protocols (EtherNet/IP, Modbus TCP, PROFIBUS) to extract diagnostic data. Both E+H and Krohne offer extensive digital integration.

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The key differentiator is the depth of data available. Can the SCADA system read the “Electrode Coating Detection” status? Can the “Empty Pipe” alarm be distinguished from a general fault? Specifications must explicitly state which variables are to be mapped to the PLC, not just “digital communication provided.”

Maintainability, Safety & Access

Chemical storage tanks are confined spaces. Instrumentation that requires removal for calibration poses safety risks and operational downtime. Non-contact radar is superior to ultrasonic or hydrostatic pressure sensors in this regard, as radar is generally unaffected by vapors and does not require entering the tank for maintenance.

Remote mount transmitters are recommended for chemical feed applications. Keeping the electronics away from potential leaks at the flange connections protects the expensive components and allows operators to read displays safely from eye level rather than climbing ladders or crouching behind pump skids.

Lifecycle Cost Drivers

While the CAPEX difference between a high-end E+H Promag and a mid-range competitor might be 20%, the OPEX implications are vast. A meter with 0.2% accuracy versus 0.5% accuracy can save thousands of dollars annually in unnecessary chemical consumption for large plants. Additionally, “Heartbeat” (E+H) or “Opticheck” (Krohne) verification technologies allow for regulatory compliance verification without removing the meter from the line, saving significant labor hours and process interruption costs.

COMPARISON TABLES

The following tables provide a direct engineering comparison to assist in the Krohne vs Endress+Hauser Chemical Feed & Storage Equipment: Comparison & Best Fit decision process. Table 1 focuses on the specific product lines relevant to this sector, while Table 2 outlines application suitability.

Table 1: Manufacturer & Product Line Analysis

Table 2: Application Fit Matrix

ENGINEER & OPERATOR FIELD NOTES

Real-world experience often diverges from catalog specifications. The following notes are compiled from field observations regarding Krohne vs Endress+Hauser Chemical Feed & Storage Equipment: Comparison & Best Fit integration.

Commissioning & Acceptance Testing

Factory Acceptance Tests (FAT): For critical chemical dosing skids, require a wet calibration at the factory. Standard “dry” electronic calibration may not suffice for non-Newtonian fluids like polymer. Ensure the calibration certificate references the specific serial number of the unit.

Site Acceptance Tests (SAT):
1. Zero Point Calibration: This is critical for magmeters. The pipe must be full of liquid but at zero flow. A common error is zeroing the meter with an empty pipe or a partially full pipe, which offsets the entire calibration curve.
2. Conductivity Verification: Verify the chemical’s conductivity meets the minimum threshold (typically >5 µS/cm for water, but often >20 µS/cm for certain magmeters).
3. Damping Settings: Adjust the damping (time constant) to smooth out the pulsating flow from metering pumps. A value between 3 to 5 seconds is a typical starting point.

Common Specification Mistakes

Oversizing the Meter: Engineers often match the flow meter size to the line size (e.g., 2-inch pipe = 2-inch meter). In chemical feed, flow rates are low. A 2-inch meter operating at 0.5 GPM will be at the very bottom of its range, resulting in poor accuracy and unstable control. Always size the meter based on the flow velocity range (ideally 2-10 ft/s), not the pipe size. It is common to reduce the line size at the meter (e.g., 2-inch pipe down to 0.5-inch meter) to increase velocity and accuracy.

Ignoring Grounding: Plastic pipes (PVC/CPVC) do not conduct electricity. For a magmeter to work, the fluid potential must be referenced to the sensor. Failing to specify grounding rings (or referencing electrodes) results in a wandering signal. Krohne’s “Virtual Reference” feature on specific models can eliminate the need for grounding rings, which is a major installation advantage in corrosive plastics.

O&M Burden & Strategy

Preventive Maintenance (PM):
– Monthly: Check transmitter display for error codes. Verify local reading matches SCADA.
– Quarterly: Inspect cable glands for chemical corrosion (chlorine attack on rubber seals).
– Annually: Perform electronic verification (Heartbeat/Opticheck). Compare totalizer readings against tank drawdown (volumetric check).

Spare Parts: Chemical feed sensors are critical path. Lead times for exotic materials (Tantalum electrodes, Ceramic liners) can be 8-12 weeks. Plants should stock one spare flow meter for each critical pipe size/type, or use “universal” spares where possible (e.g., stocking a high-spec unit that covers multiple lower-spec applications).

Troubleshooting Guide

• Symptom: Flow reading fluctuates wildly (noisy signal).
  • Root Cause: Air entrainment, electrode coating, or improper grounding.
  • Fix: Verify pump suction isn’t drawing air. Check grounding rings. Increase damping.

• Symptom: Level reading stuck at top of tank.
  • Root Cause: Radar lost echo or locked onto condensation near the antenna.
  • Fix: Check antenna condition. Increase “blocking distance.” Verify tank venting isn’t creating pressure that obscures the signal (rare for radar, common for ultrasonic).

DESIGN DETAILS / CALCULATIONS

Engineering the correct installation is as important as selecting the brand. Here are the design details pertinent to the Krohne vs Endress+Hauser Chemical Feed & Storage Equipment: Comparison & Best Fit discussion.

Sizing Logic & Methodology

To properly size a magnetic flow meter for chemical feed:

1. Determine Peak and Minimum Flow: Obtain the metering pump’s max capacity and the minimum required dose.
2. Calculate Velocity: Use the formula (V = frac{0.4085 times Q}{d^2}) where (V) is velocity (ft/s), (Q) is flow (GPM), and (d) is inner diameter (inches).
3. Target Velocity: Select a meter diameter that yields a velocity between 2 and 15 ft/s at normal operating flow.
   • Note: Velocities below 1 ft/s allow solids (lime, polymer) to settle and coat electrodes.
   • Note: Velocities above 20 ft/s can cause liner abrasion.

4. Check Pressure Drop: If reducing the meter size significantly, calculate head loss to ensure the metering pump has sufficient discharge head.

Specification Checklist

When writing the spec, ensure the following are included to avoid change orders:

• Liner Material: explicitly defined (e.g., “PFA or Ceramic”). Do not allow “Manufacturer Standard.”
• Electrode Material: defined based on chemical safety data sheet (SDS).
• Flange Rating: ANSI 150# is standard, but verify matches piping spec.
• Power Supply: 24VDC is safer and standard for instrumentation; 120VAC requires different conduit separation.
• Cable Length: For remote transmitters, specify the cable length required to reach the operator panel.
• Certifications: NSF-61 for all wetted parts if dosing into potable water.

Standards & Compliance

• AWWA C704: Standard for Propeller-Type Meters (less relevant here, but M6 manuals cover Magmeters).
• NSF/ANSI 61: Drinking Water System Components – Health Effects. Mandatory for potable water contact. Both Krohne and E+H offer NSF-61 certified liners.
• NEMA 4X / IP67: Minimum enclosure rating for washdown areas.
• NEC Article 500: Hazardous location classification (e.g., Methanol feed is Class 1, Div 1).

FAQ SECTION

What is the difference between Krohne’s Virtual Reference and E+H’s Grounding Electrodes?

In electromagnetic flow meters, the fluid potential must be equalized with the sensor body for accurate measurement. E+H typically uses a dedicated grounding electrode (a third electrode in the tube) or external grounding rings to achieve this. Krohne’s “Virtual Reference” allows the meter to operate without grounding rings by using an advanced input amplifier circuit that measures the potential difference relative to the ungrounded liquid. This reduces installation cost and leak points, particularly in plastic piping systems common in chemical feed.

How do you select between Ultrasonic and Radar for chemical storage tanks?

Radar is generally superior for chemical storage. Ultrasonic sensors rely on sound waves traveling through air; vapors from chemicals (like Hydrochloric Acid or Ammonia) change the speed of sound, causing measurement errors. Vapors can also absorb the signal. Radar (electromagnetic waves) is largely unaffected by vapor, pressure, or temperature changes in the headspace. While Ultrasonic is cheaper, the lifecycle reliability of Radar in chemical service makes it the best fit for Krohne vs Endress+Hauser Chemical Feed & Storage Equipment decisions.

What is the typical lifespan of a magmeter in Ferric Chloride service?

Ferric Chloride is highly abrasive and corrosive. A standard PTFE-lined magmeter might last 3-7 years depending on velocity and solids content. However, using a high-purity Ceramic measuring tube (a strength of Krohne’s Optiflux 5000 series) can extend this lifespan to 15+ years because the ceramic is nearly diamond-hard and chemically inert. The limitation is thermal shock; ceramic cannot handle rapid temperature spikes.

Does Endress+Hauser Heartbeat Technology replace wet calibration?

Not entirely, but it extends the interval. Heartbeat Technology performs an internal verification of the electronics and magnetic circuit with high coverage (often >95%). Regulatory agencies (like the EPA or state equivalents) are increasingly accepting “electronic verification” reports to extend the requirement for physical wet calibration or pull-checks. However, most permits still require a physical drawdown test or comparison against a master meter every 3-5 years.

Why is minimum flow velocity critical for chemical feed flow meters?

Operating a magmeter below 1 ft/s (0.3 m/s) significantly degrades accuracy (signal-to-noise ratio drops). More importantly, in chemical applications like lime slurry or polymer, low velocity allows buildup to form on the electrodes. Once electrodes are coated, the signal is insulated, causing the meter to read zero or drift. Sizing the meter smaller than the pipe to maintain >2 ft/s velocity is a standard engineering best practice.

How does “Entrained Gas Management” impact chemical dosing accuracy?

Sodium Hypochlorite and Hydrogen Peroxide naturally off-gas, creating bubbles in the feed line. Standard Coriolis or Magmeters may stall or output error values when bubbles pass through. Krohne’s EGM (Entrained Gas Management) allows the meter to maintain measurement even with high gas void fractions. E+H has similar multi-frequency technology. Without this feature, pumps may trip on “flow failure” alarms falsely due to bubbles, causing disinfection interruptions.

CONCLUSION

The choice within the Krohne vs Endress+Hauser Chemical Feed & Storage Equipment: Comparison & Best Fit matrix ultimately depends on the specific chemical profile and the plant’s maintenance philosophy. Both manufacturers offer top-tier, reliable instrumentation that exceeds the capabilities of lower-cost alternatives.

Krohne typically holds an edge in applications requiring extreme mechanical robustness, such as highly abrasive slurries or vacuum conditions where their fused ceramic liners provide unmatched durability. Their Virtual Reference technology also simplifies installation in the plastic piping systems ubiquitous in chemical feed.

Endress+Hauser often leads in terms of user interface, digital integration, and diagnostic accessibility. Their Heartbeat Technology is a benchmark for predictive maintenance, allowing operators to see electrode coating buildup before it causes a failure. For facilities prioritizing Industry 4.0 integration and ease of use for less specialized technicians, E+H is a strong contender.

Engineers should treat the flow meter and level transmitter not as accessories, but as the primary control authorities of the chemical feed system. Investing in the correct liner material, proper sizing, and advanced diagnostics yields a Return on Investment measured in process uptime, chemical savings, and regulatory compliance.