6News

ChemicalsIndustrial Weighing & Product Inspection

Hazardous-area regulations and standards have been updated in the aftermath of recent

plant explosions to reduce the risk of such accidents. We take a closer look at the recent

changes and provide practical advice for safe weighing in explosive environments.

Hazardous-Area Regulations TighteningAre You at Risk?

requiring them to comply with these guidelines.

• The Canadian Electrical Commission now requires the three-zone system for all new hazardous-area installations.

• A new International Electrotechni-cal Commission Explosive (IECEx) standard now requires certification from notified bodies for non-electri-cal equipment.

• The American National Fire Protection Association (NFPA) has introduced a combustible dust standard 652 that now requires dust-hazard analysis.

Get practical safety tips from a hazardous area expert on page 2.

In the wake of large disasters, such as the 2015 chemical explosion at Tianjin Har-bor in China, public attention often leads to tighter regulations. Existing legislation is scrutinized for gaps and weaknesses and the implementation of standards and regulations is supervised more diligently.

Several standards and regulations re-cently have been updated to close exist-ing gaps and to align with other regula-tions, including:• The EU directive 2014/34/EU aligns

to the New Legislative Framework. A noteworthy update is that end users who design their own systems can be considered equipment manufacturers

METTLER TOLEDO Chemicals News 62

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Publisher / ProductionMettler-Toledo GmbHIndustrial DivisionHeuwinkelstrasseCH-8606 NänikonSwitzerland

Subject to technical changes© 02/2017 Mettler-Toledo GmbH

Testing of hazardous-area equipment is essential to ensure a safe weighing workplace.

No Compromises on SafetyPractical Tips from a Hazardous Areas Expert

Recent changes to hazardous-area standards and regulations raise questions about the im-

plications for chemical manufacturers. We sat down with Richard Schuller, lead assessor

and certification manager at DEKRA, a world-leading expert organization. He explains what

production managers and safety officers have to consider for a safe weighing workplace.

Are such issues less common with intrinsically safe solutions? Each type of protection requires its own knowledge. Intrinsically safe solutions, for example, depend on the accurate use of barriers between hazardous and safe areas. That said, if an intrinsically safe system has been correctly installed, the incident risk during operation and main-tenance is lower compared to other pro-tection methods.

How do recent regulatory changes impact equipment users? Global standards organizations and na-tional authorities are harmonizing and tightening regulations to raise safety lev-els and simplify international trade and production. Some regulations are targeted at equipment users, such as the recently updated Canadian Electric Code (CEC), which now requires the use of the inter-national Three-Zone system for all new installations. Other regulations address

What are the main causes of accidents in hazardous areas?The main cause, by far, of accidents in hazardous areas is human error. Most often it is lack of knowledge and training that leads to negligence and carelessness. All in all, it comes down to insufficient quality control. Proper training, such as IECEx 05 Personnel Competence, prevents many problems.

Can you give an example of the most common problems?Typical problems we see at inspections in-clude flame-proof enclosures with miss-ing bolts, cable glands with missing sealing, or the wrong combination of pro-tection types, such as flame-proof enclo-sures (Ex d) with increased safety cable glands (Ex e).

METTLER TOLEDO Chemicals News 6 3

equipment manufacturers, such as the new IECEx standards on non-electrical equipment (IEC 80079-36 and 80079-37). They close a gap that allowed equipment manufacturers to “self-certify” non-elec-trical devices.

Why is non-electrical equipment considered a hazardous-area risk?Non-electrical equipment was considered an ignition source already under ATEX. For example, rotating parts or movable parts, such as springs and drive belts, can generate heat or static electricity from friction. Devices based on a light metal (e.g. aluminum) construction can gener-ate sparks on impact, for example when tools are dropped.

What are the responsibilities of equipment users to ensure safety?The equipment user has to fulfill four key aspects to ensure safety and regulatory compliance in hazardous areas: 1. Accurate classification of the hazard-

ous area into zones or divisions2. Correct installation of the equipment

by competent persons3. Implementation of safe operations

through training and standard oper-ating procedures and

4. Regular verification if the equipment and its components are functioning properly.

What are the responsibilities of the equipment manufacturer and DEKRA in the certification process?Initially, the manufacturer must design the equipment in accordance with stan-dards and regulations. When they apply for a certificate, the manufacturer must provide technical documentation and a description that details the compliance with the protection types used.

At DEKRA, we verify if the analysis was done correctly and, if applicable, imple-ment test programs. For example, we test seals and perform impact and aging tests. When all tests have been completed satis-factorily, we conduct an internal review to ensure all processes were followed and no mistakes were made. Finally, we issue the certificate and the equipment can be re-leased to the market.

www.mt.com/ind-intrinsic-safety-ch

The Most Common Errors in Hazardous-Area Installations

1. Wrong or poorly designed equipment is unsuitable for specific environmental conditions.

2. Poor or no maintenance on Ex d enclosures facilitates corrosion of the protection.

3. Incorrect installation of Ex d cable glands enables flame propagation in case of an in-ternal explosion.

4. Missing separation of Ex i and non Ex i circuits or incorrect earthing jeopardize intrinsic safety of circuits.

5. Ingress of water in Ex e enclo-sures due to condensation can cause short circuits and gener-ate sparks or fires.

Richard SchullerLead Assessor /

Certification Manager

DEKRA Certification

B.V, Netherlands

Richard is an expert in hazardous areas. During the past 16 years, he worked in various roles. He has worked as an engineer of intrinsically safe and flame-proof equipment and as a project manager for intrinsically safe equipment. Those roles were followed by his position as Auditor for Quality Management Systems of Man-ufacturers and Certification Manager for Explosion-safe Equipment.

DEKRA is one of the world‘s leading expert organizations with more than 37 000 employees in 50 countries. DEKRA is Notified Body for the ATEX Directive, is ac-credited as a Certification Body and Test Laboratory for the IECEx Scheme and accredited by INMETRO/CGCRE Brazil. In addition, DEKRA has agreements with FM and QPS (North America), KGS, KTL, KOSHA (South Korea) and TIIS (Japan) to assess equipment according to local standards.

www.dekra-certification.com/explosion-safety

METTLER TOLEDO Chemicals News 64

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Ensuring the safety of your weighing process is your first priority. However, compromises

often need to be made in terms of measurement accuracy and functionality. Our new solu-

tions are globally approved for explosive environments and provide you the tools for safe

weighing with the highest performance.

PBK9/PFK9 weighing platformsThe line of PBK9 bench and PFK9 floor scales provides a new level of measurement accuracy in hazardous areas with a rec-ommended resolution of up to 750,000d. The weighing plat-forms are certified for Zone 2/22 and Division 2 and ensure safe and reliable measurements when weighing tolerances are tight. Ap-plication examples include formu-lation and dosing of critical mate-rials, weighing of gases or filling of expensive products.

www.mt.com/pbk9-ch

www.mt.com/pfk9-ch

Achieve high accuracy in explosive environments

Bring full functionality into the hazardous area

Speed up your hazardous-area checkweighing

IND570 weighing terminalThe IND570 weighing terminal is constructed and approved for the harshest industrial environments and for use in hazardous areas classified as Zone 2/22 and Divi-sion 2. The terminal provides flex-ible control options for manual and automated processes. The IND570 can be easily expanded with software modules and com-munication and control interfaces to meet your changing process requirements.

  www.mt.com/ind570-ch

Chain checkweigherDesigned to run at speeds of up to 800 packs per minute, chain checkweighers provide fast, flaw-less transport and high-speed weighing of tall, potentially un-stable products with a small foot-print, such as aerosol cans. Sys-tems are available as ATEX Zone 2/22 certified for use in hazard-ous locations. Design features in-clude pressure-tight encapsula-tion of control cabinets and the use of anti-static materials in the operator terminal and conveyor construction.

www.mt.com/chain-checkweigher-ch

Safe by DesignNo Compromising Performance

METTLER TOLEDO Chemicals News 6 5

Zero Waste, Zero RejectsCheckweighing for Quality Control

Ensuring every product is correctly weighed and compliant with regulations while eliminat-

ing waste – those were the goals of a leading tile adhesives and grout manufacturer. The

company has achieved them using dynamic checkweighing.

cells and driven parts, such as the de-flection roller bearings, keep out dust. Those features are available as standard on the basic machine. Head of Produc-tion Klaus Weluda says his experience with METTLER TOLEDO checkweighers has been a positive one. “We have been extremely satisfied with the products and the technical customer service they pro-vide,” he says.

www.mt.com/checkweighing-ch

Forward-thinking German manufacturer Lugato GmbH & Co. KG uses a METTLER TOLEDO XS40 checkweigher to control the specified nominal weight of packs of powdered adhesives and grout. The checkweighers help to ensure compliance with FertigPackV (FPVO) regulations for pre-packaged goods in Germany.

Continuous checkingThe XS40 system checks the weight of every stand-up bag-in-box package prior to closure. Any underweight packs are

removed from the production line by a pusher mechanism. Rejected products are collected on a roller conveyor, weighed again on a static scale and manually re-filled as necessary. Then, they are fed back into the product flow upstream of the XS40 and undergo the inspection process again. That results in no product waste and the final reject amount is virtually zero.

A challenging environmentThe checkweigher’s work environment is particularly demanding. Sealed load

METTLER TOLEDO Chemicals News 66

White Paper: Control Residual IsocyanateFor more detailed information on how to minimize hazardous residual isocya-nate in polyurethane polymerizations, download our white paper here:

www.mt.com/isocyanate-white-paper-ch

Isocyanates are the essential building blocks for high performance polyurethane-based

polymers that make up coatings, foams, adhesives, elastomers, and insulation. Inline spec-

troscopy offers a way to monitor reactions in less time and with lower exposure risk than

traditional offline analyses.

Process understanding with in situ FTIRFortunately, in situ monitoring with pro-cess analytical technology is able to over-come these challenges. Specifically, in situ mid-IR spectroscopy (ReactIR™) with an attenuated total reflectance (ATR) sensor is an ideal choice due to its selectivity and sensitivity. Inline spectroscopy offers a straightfor-ward method to monitor reaction initi-ation, progression, conversion, interme-diate transient and/or highly reactive formation, and end-point in real time. This enables manufacturers and formu-lators to ensure that product quality spec-ifications, personnel safety, and environ-mental regulations are met.

In this case study a diisocyanate reacts with a polyol (Scheme 1). Several critical process parameters may affect the resid-ual diisocyanate in the product includ-

ing temperature, quality of the incoming starting material, feed rates, reaction ki-netics, and reaction time.

Real time reaction trackingTo track reaction progression, a ReactIR probe was inserted directly into the vessel for the duration of the batch. Mid-infra-red spectra depict how a decrease in reac-tants is concurrent with an increase in the product as time progresses.

The reaction components are easily de-tected by the distinct peaks as shown in Figure 1 (using conclusive functional group peak assignment, peak at 2270 cm-1 is the NCO functional group of the reactant while peak at 1740 cm-1 is the C=O functional group of the prepolymer). Reaction progression, a plot of the relative concentration of each reaction compo-nent as a function of reaction time is de-picted in Figure 2.

As manufacturing volumes rise, concerns have increased over both product qual-ity and the health impact of toxic resid-ual isocyanates. Traditional analytical methods for measuring residual isocya-nate (NCO) concentrations using offline sampling and analysis are limited by the following:

Long waiting times for results make it impossible to take real-time decisions, leading to inconsistent product qual-ity. Exposure to NCO samples increase the likelihood of sensitization and poses a risk to human health.

Controlling for Residual Isocyanatesin Polyurethane Polymerizations

Reac

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Anal

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METTLER TOLEDO Chemicals News 6 7

Scheme 1. Diisocyanate reaction to form a prepolymer.

+ + + KBr

Substrate Product

Pd(OAc)2, Ligand

t-Amyl Alcohol, reflux102 °C R1

O

OH

O

OKN

NN

CNR1 N

Br

NN

CN

Figure 2. Two dimensional peak profiles trending reaction components over time.

Figure 1. 3D Waterfall plot tracking the reaction from Scheme 1 over time.

Abro

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Diisocyanate (2270 cm-1 NCO)Prepolymer (1740 cm-1 C=O)Polyol

Wavenumber (cm-1)

Abro

rban

ce

Time (hr)

PrepolymerRt - (NCO)2

It is possible to make use of the continu-ous trends depicted in Figure 2 to set pro-cess control limits on the reaction pro-gression for each reaction component. If a trend deviates from the optimum or

expected values, the in situ measurement can immediately detect the change, which allows engineers and plant operators to make the necessary corrections during manufacture of the prepolymer. Such ac-

tionable information available in real time reduces or eliminates the potential for out-of-spec batches, reducing or elim-inating the need to re-work batches that don’t meet quality standards.

} www.mt.com/isocyanate-ch

Time (hr)

METTLER TOLEDO Chemicals News 68

Calib

ratio

n How to Optimize Calibration Efforts With a Risk-based Approach

Regular calibration based on a thorough process-risk assessment helps stabilize produc-

tion while conserving time and resources. Testing too infrequently risks undetected accu-

racy problems, while testing too often interrupts production. Find out the right schedule for

you in just two minutes and comply with the new ISO 9001 risk-based thinking approach.

Optimize calibration effortsA systematic risk-based review of your weighing process may be the most im-portant step an organization has to take to optimize calibration effort and comply with the revised ISO 9001 standard.

METTLER TOLEDO has developed Good Weighing Practice™, a standardized sci-entific methodology for secure selection, calibration and operation of weighing equipment based on a thorough risk anal-ysis. During a consultation, our GWP® experts help you objectively assess risks related to your weighing equipment and develop the right risk-management pro-cess to prevent failures before they occur. Eliminate unnecessary testing when risks are low and ensure top performance when risks are high. We also provide the full documentation for a smooth transition to ISO 9001:2015.

Learn more about Good Weighing Practice (GWP) and calibration:

www.mt.com/gwp-verification-ch

www.mt.com/calibration-ch

The 2015 revision of ISO 9001 has brought a major change regarding the risk-based thinking approach that is found through-out the entire standard. It also impacts the calibration process. The only way to ensure that measurements deliver the kind of cost, quality and revenue results that help improve profitability is to choose the right procedure and schedule to peri-odically re-calibrate your scale. However, industrial environments are tough on weighing equipment. If scales fail or de-liver inaccurate measurements, you risk production downtime, poor product qual-ity, regulatory non-compliance, increased liability and potential profit losses.

Risk-based thinkingMany companies are already familiar with risk-based thinking from other stan-dards, such as Good Manufacturing Prac-

tice or safety standards. Risk is usually analyzed in two parts: The likelihood (probability) that it happens and the se-verity (impact) if something happens.

Impacts on calibrationTranslating risk-based thinking into the calibration process starts with evaluating the impact of inaccurate weighing results on your business process. Examples are loss of material and time, out-of-specifi-cation results, production stops, product recall and reputational damage. Addition-ally, the impact of wrong measurements on people and the environment has to be assessed. Finally, you must estimate how probable the detection of the faulty mea-surement is. The more accurate a weigh-ing process has to be, and the higher the negative impact of faulty measurement, the more testing is required.

The higher the required weighing accuracy and business impact of faulty measurements, the more testing is needed.

Accu

racy

(+/-) 0.01% Medium Serious High High

0.1% Medium Medium Serious High

1% Low Medium Medium Serious

10% Low Low Medium Medium

Weighing

Risk

Minor Moderate Significant Severe

Business impact of inaccurate measurements

Weighing Risk Assessment Matrix

METTLER TOLEDO Chemicals News 6 9

New Requirements: ISO 9001:2015

The most relevant update is the introduction of risk man-agement in the quality man-agement process. Risk iden-tification, assessment and management are key activ-ities to maintain quality. To maintain their ISO 9001 cer-tification, companies need to adapt to the new standard by September 2018.

www.mt.com/ind-iso9001-ch

Recommended Performance Verification ActivitiesService ContractMaintenance and repair YearlyTestsCalibration (by service) YearlyMinimum weight certificate YearlyLinearity YearlyEccentricity (by user) –Repeatability (by user) QuarterlySensitivity (by user) WeeklyWeightsWeight 1 1 000 kg Class M2 or betterWeight 2 100 kg Class M2 or betterRecalibration interval of weights Every two yearsTest TolerancesSensitivityWeight 1 Warning limit 1.66 kg

Control limit 5 kgRepeatabilityWeight 2 Warning limit 0.25 kg

Control limit 0.75 kg

Risk Assessment UnitWeighing accuracy 1%Impact of wrong measurements on business process MediumImpact of wrong measurements on humans, animals and on the environment LowWrong measurements can be discovered easily No

Example of a GWP® Verification for a scale including the risk assessment and recom-mended testing activities.

METTLER TOLEDO Chemicals News 610

Glass XEROLYT®Measuring solution

Glass

Measuringsolution

Openjunction

Xerolyt® Extrasolid polymer

electrolyte

InPro 4260 i pH sensor with solid electrolyte

Dramatic Reduction in Sensor MaintenanceIntelligent Solution Surpasses Expectations

InPr

o 42

60 i

pH S

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Scrubbers are tough environments for pH sensors. Switching to a METTLER TOLEDO so-

lution with Intelligent Sensor Management (ISM®) has dramatically reduced measure-

ment point running costs for a US chemical company. Now, the need for calibration has

dropped by 70 %.

erated blindly. Further, the probes were surviving for no more than three months.

Reliability and longevity areessentialThe customer began looking for reliable sensors with a minimum lifetime of six months. They also wanted a retractable housing that would allow extraction of the sensor while the scrubber was operating.METTLER TOLEDO supplied a system that far surpassed our customer s̓ expectations.

Amine producerOur customer is a USA producer of spe-cialty amines used in the manufacture of agricultural chemicals, biocides, and other intermediate chemicals. In its pro-duction processes, ethylene oxide is used as a feedstock. Due to its toxicity, any fu-gitive emissions of unreacted ethylene oxide in off-gas must be removed before the exhausts can be released. For this, the exhaust is scrubbed with a sulfuric acid solution.

Measurement frustrationTo determine correct acid dosing in the scrubber, technicians use in-line pH sen-sors. However, the frequent maintenance and calibration required for the probes they were using were causing frustration. If operators received unreliable read-ings, instrumentation personnel had to be called out to maintain or replace the probe. This meant that during sensor maintenance, the scrubber was being op-

METTLER TOLEDO Chemicals News 6 11

High performance sensorThe InPro 4260 i is the ideal pH sensor for this process. It features Xerolyt® solid polymer electrolyte, which provides a long lifetime and accurate measurement even in the harshest scrubber environments. To meet customer requirements, the sen-sor was mounted in an InTrac 787 retract-able housing.

Maintenance known in advanceFor the transmitter, an M400 has been in-stalled. This is a single-channel, multi-parameter unit with ISM technology. ISM plays a significant role in this application. It features diagnostic tools that continu-

ously monitor the installed sensorʼs con-dition. These tools are displayed on the M400 transmitter and forwarded through the plantʼs control system for remote monitoring. Two key tools, the Adaptive Calibration Timer (ACT) and Dynamic Lifetime Indicator (DLI), mean instru-mentation personnel know when the sen-sor will need calibrated or replaced.

All ISM sensors, including the InPro 4260 i, retain their own calibration data. This provides our customer with another significant benefit. If the installed sen-sor requires calibration, it can be quickly swapped at the measurement point with a

… calibration has changed from a monthly process to being conducted every three to four months.

second sensor that has already been cali-brated. Therefore, there is no break in the measurement.

More than 18 months without a hitchThe METTLER TOLEDO solution has been running for over a year and a half, and the original InPro 4260 i sensors are still working reliably. The customer also re-ports that calibration has changed from a monthly process to being conducted every three to four months. The benefits of ISM have convinced the customer to install similar systems elsewhere in their facility.

www.mt.com/InPro4260i-ch

For more informationwww.mt.com/ind-chMettler-Toledo GmbH

Industrial DivisionCH-8606 Nänikon, Switzerland

Local contact: www.mt.com/contacts

MTSI 30312939

No SurprisesReal-time Equipment Monitoring

Don’t wait for Industry 4.0 to happen. Start monitoring the performance of your weighing equipment today with InTouchSM Remote Services. Connected scales send proactive alerts that enable you to immediately respond to performance issues.

Increase uptime and ensure consistent measurement quality.

For more information about Real-time Equipment Monitoring visit:

www.mt.com/ind-intouch-remote-ch

Security without Compromise• ISO27001-2013 certification• User authentication and

access control• No changes to existing IT or

security infrastructure

Efficient Equipment Management• Real-time equipment status

information• Fact-based timing of preventive

maintenance activities

Improved Performance Control• On-going monitoring of

measuring performance• Periodic asset status reports

to optimize processes

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