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Manual Weighing System MWS-1

Climate-controlled manual weighing system with RFID technology for the gravimetric assessment of sampling filters

The manual weighing system MWS-1 provides a contamination-free working environment for the manual weighing of sampling filters. Integrated RFID technology identifies and tracks the filters during the entire process. If a PC is connected, the weighing results are recorded in a database along with relevant ancillary data, such as temperature and relative humidity. A weighing chamber with a fan filter unit (FFU) and climate control unit maintains controlled, dustproof conditions throughout the weighing operation. Its modular design allows the system to be adapted to customers’ specific requirements.


Key Features

  • Significant reduction in incorrect readings
  • Capture and recording of weighing results
  • Dustproof weighing chamber
  • Filter coding and identification by RFID
  • Ducts with oversleeves
  • Filter magazine for storing filters
  • Temperature and humidity control
  • Ionization fan (optional)


System configuration

The manual weighing system MWS-1 consists of the following principal components:

  • Dustproof weighing chamber with:
    • Filter disc magazines for holding filters before and after weighing
    • Ultra-microbalance (optional, most existing balances can be integrated after modification)
    • Fan filter unit (FFU) to protect the weighing chamber against contamination
    • RFID station for coding and identifying filters
    • Ionization system for neutralizing the filters (“eliminating” static electricity) (optional)
    • Climate control unit
  • PC and monitor for operating the system (optional)
  • Control and power supply cabinet underneath the weighing chamber

Operating principle and weighing process

Before the first weighing operation is performed, the unladen sampling filters are placed in filter trays by hand and introduced into the weighing chamber of the MWS-1. In order to identify the filters, they are held above the RFID station in their individual filter trays and coded in a contactless operation. They are then placed in the filter magazine and conditioned for the desired time.

The next step is the first weighing series, which consists of weighing the unladen filters, usually in two weighing passes. The optional ionization system neutralizes the filters (“eliminates” the static electricity) and thus enhances weighing accuracy. Once the unladen filters have been weighed, they are taken out of the weighing chamber and made ready for sampling.

After sampling, the filters are returned to the filter trays, introduced into the weighing chamber and conditioned again. The second weighing series (weighing the laden filters) follows, once again with two or possibly three weighing passes. Previously coded filters can be identified by the RFID station, which allows the laden reading to be compared directly with the preceding unladen reading. Both before and during the weighing series, verification weighing operations can be performed with reference filters in order to monitor the climatic conditions inside the weighing chamber. During the weighing operation, all the data (weighed values, mean values, weight difference between unladen and laden filters, and ancillary data, such as temperature and relative humidity) are saved in the database on the system PC.

The saved data can subsequently be exported for analysis and processing. The concentration of particulate matter in the exhaust gas is calculated from the weight difference between the laden and unladen filters, giving consideration to the air flow rate during the collection period.


Compared with lab weighing, the MWS-1 offers the benefits of a contamination-free workplace designed specifically for weighing filters. The connected system PC facilitates reliable recording of the weighing results, comparisons between individual weighing passes, and continuous monitoring of the climatic conditions. The system rules out inaccurate records and delivers reliable, precise results by manual weighing. An integrated filter magazine can accommodate a large number of filters in a protected environment. The optional climate control unit maintains the necessary climatic conditions throughout the entire process.

Detailed information is contained in the data sheet “Manual Weighing System MWS-1”.


The information on this website represents the state of knowledge at the time of writing. Technical specifications are subject to modifications. Comde-Derenda GmbH accepts no liability whatsoever for the content provided or for damages resulting from the use of its products.

Technical Data

Filters and filter trays
Filter material Glass fiber, quartz fiber, cellulose nitrate, Teflon
Filter sizes System modifiable for all common filter sizes
Filter encoding Via RFID system and RFID transponders in the filter trays
Filter identification Non-contact identification using RFID technology
Filter magazine Number of magazine discs 25
Number of filters per magazine disc 15
Total filter capacity 375
Potential equilization Through consistent conductive design
Mikrobalance (optional) Integrable models Microbalances and ultra-microbalances manufactured by Sartorius or Mettler-Toledo (others upon request)
Readability (resolution), depending on balace model 0.001 or 0.0001 mg
Maximum load 20 / 22 g
Balance placement On platform with a large mass (approx. 150 kg), decoupled from system structure
Calibration weights Integrated in the balance
Weighing repeatability (reference weights) 1 σ ≤ 0.25 µg (when using the Sartorius Cubis® weighing cell)
Weighing repeatability (filters) 1 σ ≤ 1.5 µg (when using the Sartorius Cubis® weighing cell)
Additional specifications Cleanroom class (within the weighing chamber) 6
Electronics Interface LAN (RJ-45)
Data export TCP/IP (example) Weight of unloaded filter (average value)
Weight of loaded filter (average value)
Difference of weight between unloaded and loaded filter (average value)
Temperature, rel. humidity, barometric pressure
Filter number, sampler number, number of weighing per filter
Power supply
Power source 230 V ± 10 %, 50 Hz
Power requirement (without chiller unit) approx. 1800 VA
Power requirement chiller approx. 1300 VA
Dimensions Width 1190 mm
Height with protective hood 1995 mm
Height of work surface 875 mm
Depth 930 mm
Weight (incl. balance platform) < 650 kg
Weight external chiller < 75 kg
Climate control
Temperature regulation Climate control unit (heating, cooling, humidification, dehumidifica­tion), with external water connection and external compressor
Humidifier unit Evaporator as air cooler unit
Accuracy of temperature regulation ± 0.5 K (with set value 20 … 22 °C)
Accuracy of humidity regulation ± 2.5 % RH (with set value 45 … 50 % RH)
Accuracy of dew point regulation ± 1 K (with set value 7.7 … 11.1 °C)
Operating conditions 16 … 28 °C, 30 … 60 % rel. humidity

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