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Zellweger Impact / Impact Pro VS Crowcon Tetra

Zellweger Impact and Zellweger Impact Pro portable gas monitors have a hard time competing with the Crowcon Tetra portable multigas monitor...

Zellweger Impact and Zellweger Impact Pro portable gas detectors look good on paper, but lack the versatility and some considerations for use in the field that the Crowcon Tetra provides.  We have compared every aspect of Zellweger Impact and Impact Pro gas monitors against Tetra gas detector to determine which unit has the most to offer for the best value.

Zellweger Impact and Zellweger Impact Pro Gas Detectors


Zellweger Impact and Impact Pro vs. Tetra Gas Monitor...

When maneuvering through confined spaces, ergonomics become very important to the user's safety.  Both Zellweger Impact gas detectors have a four-button configuration and a complex menu system that makes gas detection in the field a cumbersome task.  Tetra features true single button operation with easy to see backlit graphic display for readings and diagnostics.  One good ergonomic feature shared by the Zellweger Impact, Impact Pro and Crowcon Tetra is the top reading display.  This is the best configuration for field us.  Like a pager, the user can read the instrument by glancing down at it, without removing it from where it is clipped to the person's body.

As far as sensors, the main point of a gas detector, Zellweger Impact and Impact Pro leave something to be desired.  Impact Pro gas detectors are limited to a range of 8 toxic gases.  Tetra can interchangeably use the full range of toxic gas sensors making it suitable for more applications.  Furthermore, Impact gas sensor accuracy does not meet some industry required levels, making it unsuitable for many industrial applications.  Impact H2S sensor accuracy +/- 2.5ppm, cannot set alarm at 5ppm. CO sensor accuracy for Impact and Impact Pro is +/-12.5ppm with poor accuracy for 30ppm alarm. Tetra's high quality toxic sensors alarm at industry required levels with adequate accuracy. Zellweger Impact gas detectors require an annual cartridge replacement while Tetra has a 2 year sensor life, reducing maintenance costs.  When it is time to change Zellweger Impact and Impact Pro sensors, we find the attachment clips feel like they seat poorly and are removed too easily, making them unsuitable for many industrial applications.  Zellweger Impact and Impact Pro flow heads are also difficult to fit and remove.  Tetra's sensors clip easily and securely.  Simple attachment and removal of accessories make Tetra user friendly and ultimately saves on maintenance costs.

Like most competitive portable gas detectors, Impact and Impact Pro use a visual alarm that offers only red LEDs.  The Crowcon Tetra uses both red and blue LEDs.  This provides higher visibility due to the physical nature of the colored light frequency.  Blue light has a higher frequency, emits higher energy and is proven to be brighter and more visible then red.  Psychologically, red communicates danger.  For these reasons, emergency vehicles use either blue or both blue and red flashing lights to get your attention, the same reason the Tetra uses both blue and red for gas alarms.

Zellweger Impact and Impact Pro are also outperformed by Crowcon Tetra when it comes to software.  Impact gas detectors offer no internal software conformity.  Tetra's internal software conforms to IEC 61508 standards, guaranteeing software functional safety configuration of the instrument.  The Tetra software also features password protection, which the Impact and Impact Pro do not.

Features of Tetra...

Tetra is one of the most rugged, reliable and reasonably priced portable multi-gas detectors available.  Tetra's tough, innovative design allows for rough handling in harsh environments.  Compact and lightweight (about 1 pound) Tetra offers a wide variety of features for a personal gas monitor.  Tetra is certified valid for use in temperatures up to 131F, making it the perfect instrument for use in foundries, steel mills and hot outdoor climates.

Why pay more for less?

When spending yours or your companies money, don't you want the most features for the best price?  Crowcon's Tetra gives customers durability and flexibility while maintaining simple, 1 button operation.  You can easily spend hundreds of dollars more on gas detection instruments that offer less and are difficult and confusing to operate.  Get the most from your purchasing dollars with the high quality, easy to use, cost effective Tetra.

Compare Features of Tetra with Impact/Impact Pro
  Crowcon Tetra Zellweger Impact
Number of Sensors 1-4 1-4
Sensor Types Fl, OX, Toxics FL,Ox, and toxics
Max number toxic gases 4 from total of 12 2, from a total of 8
Intelligent Sensors Yes, fully pre-calibrated No
Size 124x128x57 mm 49x84x136 mm
Weight 500g 560g
Ingress Protection IP65 IP65/IP54 Sensor
Instantaneous Alarms 2 3
TWA Alarms 8hr and 15min Yes
Alarm Tones Selectable from 5 Two Tone
Sounder Output 85dBA @ 1ft 5dBA @ 1m
Visual Alarm Red and Blue LEDs on top Rapid Red flashing LED
Vibrating Alarm Yes No
Confidence Flash Flashing Icon Green LED
Confidence Sound Every 10 seconds Yes
Low Battery Alarm Yes Yes, 20 mins
Display Simultaneous Simultaneous
Display Type Graphic LCD LCD
Peak Display Capability On Demand Yes, Menu Selectable
TWA Toxic Display On Demand Yes, Menu Selectable
Auto zero on Start Up Configurable User Confirm
Computer Interface IR Base Station
Data Logging Event Logging Event logging
Flammable Gas Factors Yes Yes
Rechargeable Battery Li-ion NiMH
Operating Time 12hrs 12hrs
Recharge Time 5 hours 4 hrs
Dry Cell Batteries AA cells Yes
Operating Time 15 hours 20 hours
Sampling Diffusion/Aspirator/Pumped Diffusion/Pumped
Electric Pump Internal, optional Optional Internal
Certification Code Rechargeable (Europe) EEx iad IIC T4 (Tamb +55degC) EEx iad IIC T4
Certification Code Dry Cell (Europe) EEX iad IIC T3 (Tamb +55degC) N/A
Temperature Rating -20 to +55 degC -20 to +50 C
Certification Code Rechargeable (US) Class I Division 1 Groups A,B,C,D Class I Division 1 Groups A,B,C,D
Certification Code Dry Cell (US) Class I Division 1 Groups A,B,C,D Class I Division 1 Groups A,B,C,D
Rubber Boot Over molded No
Carry case Yes No
Chest Harness Yes Yes
Shoulder Strap Yes No


See the Crowcon Tetra Gas Monitor or read about all Portable Gas Detectors.

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BPA is an authorized dealer of Crowcon.  BPA is not an authorized dealer of BW, ISC, Zellweger, MSA, or Draeger products.  Information about products and prices are to be used for comparisons, educational and informational purposes only.  The views and statements expressed on this page represent the opinions of the authors and should not be considered scientific conclusions. BPA assumes no liability for the information contained herein.