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A rebuttal to the ChemDAQ vs. Interscan table from ChemDAQ's website
ChemDAQ, a manufacturer of ethylene oxide (EtO) monitoring systems, has posted a pdf of a comparison matrix on its website, pitting their systems against ours. Fair...
Last Modified: 2007-06-14 Number of views: 1294
Accuracy
Definitions "Accuracy" as defined in the ANSI/ISA—51.1—1979 (R1993) standard Process Instrumentation Terminology is: [T]he degree of conformity of an...
Last Modified: 2006-09-20 Number of views: 3337
Are there any documents available that provide a frame work or guidance on when a gas detection system should be installed?
It should be noted that long before OSHA, and long before direct-reading instruments were available, people were doing toxic gas detection to protect their employees;...
Last Modified: 2007-07-21 Number of views: 1036
Best practices for certain ethylene oxide cylinder operations
This article is based on a request from Frank Denny, Director of the Office of Occupational Safety and Health of the United States Department of Veterans Affairs....
Last Modified: 2007-07-08 Number of views: 1220
Calibration Basics
Introduction It is quite unlikely that you will ever use an absolute method for gas detection. Rather, you will employ any one of dozens of "relative"...
Last Modified: 2008-01-09 Number of views: 4198
Can a carbon monoxide detector double as a propane gas sniffer?
Thanks for your question.  The answer depends on what you mean by "double," and even on how we define "detector." Usually, "detector" means the sensing element...
Last Modified: 2006-12-20 Number of views: 1522
Complying with 40 CFR Part 63 subpart WWWWW--National Emission Standards for Hospital Ethylene Oxide Sterilizers
Background In the continuing regulatory assault on ethylene oxide, more rules now apply. Fortunately, these latest statutes are not at all difficult to comply...
Last Modified: 2008-03-10 Number of views: 639
Continuous Monitoring vs. Stream-Switching Monitoring
First, let's define the terms: "Continuous" monitoring means that each sampling point is being monitored all the time, and in most cases, the concentration...
Last Modified: 2005-08-12 Number of views: 2872
Correction for Atmospheric Pressure on Gas Detection Instruments
When a gas concentration is measured or reported, we may talk in terms of ppm, but in reality we are measuring the partial pressure of the gas. (Refer to Dalton's Law...
Last Modified: 2006-08-21 Number of views: 1777
Data Logging and Data Acquisition in Gas Detection
Virtually every industrial facility has some kind of gas detection in place: Millions of portable units are in service, and at least a million points of continuous gas...
Last Modified: 2007-10-05 Number of views: 1606
Detector Tubes And When To Use Them
A detector tube is a graduated glass tube filled with a chemical reagent that will produce a color change, when exposed to the gas in question. It is used with a hand...
Last Modified: 2007-03-07 Number of views: 1357
Determining the Dew Point of a Gas Sample
"Dew Point" is defined as the temperature to which a given volume of air must be cooled at constant pressure and constant water vapor content in order for saturation to...
Last Modified: 2007-02-01 Number of views: 3058
EtO Instrumentation Calibration and Surrogate Calibration Techniques
Written in response to a particular inquiry, this article is posted since it is of general interest. Calibration is a very important issue. One of Interscan's...
Last Modified: 2008-07-23 Number of views: 3417
Hazardous Locations
Background Gas detection instruments must often be used or installed in areas considered to be "hazardous locations." Generically, all sorts of hazards...
Last Modified: 2008-02-20 Number of views: 720
I have seen two numbers relating response of Cl2 in a ClO2 detector. One is 3.1 to 1 and the other is 10 to 4, both in favor of ClO2. What is the relative response of the Interscan ClO2 detector and can Cl2 be used to spot calibrate it?
As you may know, surrogate gas calibration for chlorine dioxide is recommended because it is extremely difficult to generate a stable source of ClO 2 , especially for...
Last Modified: 2007-09-21 Number of views: 848
In Search of Zero
As discussed in the Calibration Basics Knowledge Base article, Interscan's gas analyzers, and virtually all other direct-reading gas analyzers are not absolute methods....
Last Modified: 2006-12-08 Number of views: 1657
Is there a diference between gas detector and gas monitor? If so what is the difference? How do we know that a piece of equipment is a monitor and not a detector?
In many cases, the terms "gas detector" and "gas monitor" are used interchangeably, and this can lead to confusion. When the word "detector" is mentioned in the...
Last Modified: 2007-05-20 Number of views: 1231
Is there a OSHA/DOT or any guideline/regulation that tells me how many ammonia detectors are required in ammonia storage/vaporizer and unloading area?
While guidelines may exist that mandate monitoring of an area for any number of toxic compounds, no official government recommendations are made as to the detailed design...
Last Modified: 2007-05-13 Number of views: 1029
Minimum Detectability
"Minimum Detectability" is one of those instrumentation terms that is used frequently, but is seldom defined. Indeed, even though you will encounter this term on many...
Last Modified: 2006-09-20 Number of views: 2409
More on monitoring hydrogen peroxide in sterile processing departments
This article is a follow-up to the Knowledge Base entry entitled "Monitoring hydrogen peroxide with an EtO monitoring system" . As stated in the earlier...
Last Modified: 2008-07-23 Number of views: 1380
Response time, lag time, and when it matters
Interscan provides detailed sensor response data in our Tech Center . Rise time to 90% of final value, rise time to 50% of final value, and fall time to 10% of...
Last Modified: 2005-04-19 Number of views: 2816
Understanding Danger
The dictionary defines "danger" as "the state of being exposed to harm : liability to injury, pain, or loss." Typically, gas detection is deployed in areas that contain...
Last Modified: 2006-04-07 Number of views: 2128
Using Common Sense and Science in Expressing Gas Concentrations
Go directly to conversion spreadsheets Early on, in our first chemistry classes, we learn about solutions, and different ways of expressing their concentrations....
Last Modified: 2007-09-25 Number of views: 4759
Using Interscan Analyzers For Method 21 Studies
EPA's Method 21 , entitled "Determination Of Volatile Organic Compound Leaks," calls for a portable instrument to be used for this purpose, and details certain...
Last Modified: 2005-08-11 Number of views: 2088
What international codes/standards specify the limiting allowable concentration of flammable, combustible, and toxic gases in indoor and outdoor industrial areas
Most codes and standards—at least regarding allowable concentrations of various substances—are promulgated by domestic jurisdictions, whether at the...
Last Modified: 2007-04-25 Number of views: 1302
What's a Better Methodology for a Toxic Gas Detection System—Sample Draw or Remote Diffusion?
Definitions A sample draw system uses a pump to draw sample back into the instrument, where it enters the sensor for analysis, and is then exhausted to the...
Last Modified: 2007-04-18 Number of views: 1938
When is a part-per-billion (ppb) NOT a part-per-billion (ppb)?
As if it weren't bad enough that clueless environmental authorities try to impose their ignorance on the field by using so-called "metric" units of gas concentration,...
Last Modified: 2006-04-10 Number of views: 1745
Where should I set the alarms on my toxic gas monitoring system?
Note: All exposure limits cited in this article are current as of 31 December 2006   Ultimately, the entire matter of where to set the...
Last Modified: 2007-01-31 Number of views: 4649


Best Practices (17)
A how-to clinic on gas detection apps, based on real-world experience
       


Most Viewed Articles
Using Common Sense and Science in Expressing Gas Concentrations
Go directly to conversion spreadsheets Early on, in our first chemistry classes, we learn about solutions, and different ways of expressing their concentrations....
Where should I set the alarms on my toxic gas monitoring system?
Note: All exposure limits cited in this article are current as of 31 December 2006   Ultimately, the entire matter of where to set the...
Calibration Basics
Introduction It is quite unlikely that you will ever use an absolute method for gas detection. Rather, you will employ any one of dozens of "relative"...
Monitoring hydrogen peroxide with an EtO monitoring system
For some time, ChemDAQ has been touting the supposed capability of its EtO monitoring systems to be outfitted with hydrogen peroxide sensors. That's nice, but there...
Pushing The Limits Of Hydrazine Detection At NASA
Ever since Interscan developed a portable hydrazine analyzer for Brooks Air Force Base, way back in the late 1970's, our instruments have been widely deployed in all...
EtO Instrumentation Calibration and Surrogate Calibration Techniques
Written in response to a particular inquiry, this article is posted since it is of general interest. Calibration is a very important issue. One of Interscan's...
Accuracy
Definitions "Accuracy" as defined in the ANSI/ISA—51.1—1979 (R1993) standard Process Instrumentation Terminology is: [T]he degree of conformity of an...
Determining the Dew Point of a Gas Sample
"Dew Point" is defined as the temperature to which a given volume of air must be cooled at constant pressure and constant water vapor content in order for saturation to...
Continuous Monitoring vs. Stream-Switching Monitoring
First, let's define the terms: "Continuous" monitoring means that each sampling point is being monitored all the time, and in most cases, the concentration...
Response time, lag time, and when it matters
Interscan provides detailed sensor response data in our Tech Center . Rise time to 90% of final value, rise time to 50% of final value, and fall time to 10% of...
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