DT990 - Particulate Emissions Monitoring Systems
 
 
 
* Electrodynamic Sensing
* Advanced QA / QC Checks
* Internal Calibration Checks
* Automatic Calibration Checks
 
                           (please click on a link below to go directly to that area on this page)
 
 
 		 
                                        Principles of Operation
 
The DT990 uses patented AC electrodynamic technology, an advanced triboelectric method.  The DC signal created by particles colliding with a probe inserted in a stack is electronically filtered out, leaving an AC signal resulting from charged particles passing and interacting with the rod.  Since the signal includes no DC component, the instrument has minimal cross sensitivity to changing velocity* and has increased stability even with dust build up on the rod sensor.  The dust signal is amplified, digitized and processed at the probe, consistent with good signal to noise design techniques.  The processed signal is proportional to dust concentration, although the exact correlation is application dependent.  The DT990 has had this linear relationship validated in independent certification tests (Specifically German TUV, BimSchV 17).
 
An insulated probe option is also available to minimize false signals resulting from dust build up at the base of the sensor, which can occur in process dryer and conductive dust applications.  Unlike other insulated sensors, this sensor operates with AC signal analysis, which provides measurement stability, velocity insensitivity* and tolerance to dust coating on the sensing part of the rod.
                                          *Insignificant effect for velocities between 8-20 m/s
 
 
 		 
 
                                   Advanced Probe and Q/A Checks
 
The DT990 includes the most advanced automatic functionality checks available on any probe system to provide full regulatory compatibility.  The unique contamination circuit monitors for any leakage currents or signals across the insulator, hence providing the ultimate proof that the sensors measurement integrity is uncompromised.  The auotmatic zero and span checks then provide proof that the electronic amplification and conditioning of the signal is performed within pre-defined tolerances.  The above features for a part of world wide patents.
 
 
Automatic Self-Checks
 
* Zero Check
 
* Span Check
 
* Contamination Check
 
 
Advanced signal processing techniques are used within the sensor electronics to provide the following measurement features:
 
* Rapid Dynamic Ranging of 1,000,000:1 (Dynatrack) permitting bag cleaning pulses to be accurately monitored while maintaining high accuracy in background emission measurement
 
* Proper rolling averages (rather than signal filtering) for accurate emission reporting in dynamic processes
 
* Reproducibility between sensors greater than 50 (certification range/standard deviation between 2 instruments in independent certification)
 
 
Applications
 
The DT990 is particularly suitable for bag filter, cartridge filter and dust collector applications.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                                       Satisfying MACT Standards
 
The DT990 satisfies, cost effectively, the EPA guidance procedure for fabric filter bag leak detection by reducing the ongoing cost of quality assurance activities
 
The DT990 sensor has automated zero and span checks to meet the monthly electronic drift check requirements in the EPA guidance.  This would otherwise be accomplished manually by disconnecting the probe and testing with a special signal generator (see DS550).
 
The EPA guidance also requires periodic inspection and cleaning of the probe to alleviate problems with dust build up.  But how often is this necessary?  The DT990 has a patented built-in dust build-up check (contamination check), which provides a contamination value and alarm when dust build up is a problem.  This removes the need for frequent removal of the probe for inspection which would be otherwise necessary.
 
The QA screen provides a summary of all drift check and contamination results.  Also, consistent with EPA Guidance, the instrument has two options to set alarms:
 
1.)  Using dust peak height as an early indication of filter failure.
 
2.)  Using average dust level to identify significant filter failure.  Alarm delay is used to discriminate filter failure from dust pulses arising from bag cleaning.
 
Recording of emission alarms and average emissions is built into the control unit and 'DustReporter 2' PC software is used to download the data from the control unit and produce reports.
 
Its minimum detection level of 0.01 mg/m3 easily meets the EPA requirements under the MACT Standards.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                                                 Control Unit Features
 
*  Displays instantaneous and average emissions (bargraph, text and on-line graph)
 
*  Configurable 'channel grouping' screen for displaying related data e.g. dust, velocity, 02
 
*  Monitors data from external sensors*, for normalisation and centralized analysis e.g. velocity, 02, Temp, etc.
 
*  Status screen for concise display of alarm conditions
 
*  Controls up to 32 sensors
 
*  Dual alarm levels with alarm delays
 
*  Alarm log for instrument and emission alarms
 
*  Full on instrument review of three simultaneous memories (Long Term** Short Term and Pulse, see below)
 
*  Windows software to download to PC for reporting (option)
 
*  Large, back-lit graphical display (320 x 240 pixels) for easy interpretation of graphical data
 
*  Fully calibratable in mg/m3 (when calibrated against recommended ISO tests)
 
*  Full overview of current condition of system, i.e. zero, span, probe contamination, comms
 
*  Multiple calibration factors
 
*  Multi-channel bargraph show emissions relative to alarms
 
*  Password protection
 
                                                         * Requires Optional AIM units
                                                       ** Optional Features
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                                            Control Unit Specifications
 
 		 
Multichannel support:
1 to 32 sensors
Enclosure rating:
IP65
Enclosure size (mm):
260w x 160h x 90d
Power Supply:
90 to 260 VAC (50/60Hz)
Current Rating:
250mA
Display Type:
Backlit LCD providing graphical and text display
Order Code:
DT990--CON
4 x Isolate 4-20mA Outputs
Assignable to any channel
MODBUS RS-485 & RS-232 Outputs:
Connection to PC or PLC
4 x Relay Outputs:
Configurable and assignable
4 x Digital Inputs:
e.g. Plant on/off, bagfilter, cleaning pulse, multiple calibrations
Ethernet Output:
Optional card
 
 
Note:  Local 4 - 20mA and Relay output also available from each sensor (option) and from output expansion modules (option).
 
 
                         Simultaneous Maintenance, Control and Reporting
 
Control Unit
Memory Type
Purpose
Storage Rate/
Capacity
Typical Log Period
for 8 Sensors
Long Term - Included
Calculating emission
averages (for reporting)
1 min - 2 hours
150k entries
204 days 
(@15 minutes)
Short Term
Visibility to Process Trends
1 sec - 4 mins
20k entries
20 hours
(@ 30 seconds)
Pulse - Included
Locating Broken Bags
Optimized
(13k entries)
25 minutes
Alarm Log - Included
Log of all alarms
Instantaneous
1000 entries
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                                                           Sensors
 
Sensors comprise both a sensor body and insulated or stainless sensor rods.  The tables below show order codes for the sensor body and sensor rod, which must be specified separately.  Occasionally an additional air purge is fitted for very conductive applications.
 
Temp Range
For Rod Type
For Rod Diameter
Weight
(kg)
Sensor Body Order Code
up to 250C
up to 400C
up to 250C
up to 400C
up to 800C
316 Stainless
316 Stainless
Insulated (PTFE)
Insulated (Ceramic)
316 Stainless
15 mm
15 mm
21 mm
16 mm
15 mm
1.8
1.8
1.8
1.8
1.8
DT990-SEN0250P
DT990-SEN0400C
DT990-SEN0250I
DT990-SEN0400I
DT990-SEN0800C
 
The sensor rod material is either 316 stainless steel or for humid applications (e.g. process dryer), a patented insulated rod.  To ensure representative measurement, the sensor rod is selected for a particular stackduct size (which should be specified).  Typically, the rod length is at least half the stack diameter.
 
 		 
 
Stack/Duct Connection
1 1/2" NPT or
1 1/2" BSP socket
Ambient Temperature
Rating
-25C to +55C
Enclosure Rating
IP65
Sensor Enclosure 
Material
Die-cast Aluminum
(epoxy-coated)
Air Purge (optional)
DT990--AIR PURGE
Stack Pressure
>730PSI
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                                               Optional Components
 		 
   
 
 
AIM (Analog Input Module)
Input data from external devices (e.g. Pressure Drop)
SPUR
Divides cable into 2 branches
PSU / Repeater
Voltage and signal boost for extended cabling runs, with multiple sensors
Analog Output Module
Additional 4-20 mA
Relay Output Module
Additional Relay
DustReporter 2
PC Reporting Software, runs on Windows 95, 98, NT and XP
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
PCME-US is a division of B3 Systems, Inc.
B3 Systems, Inc. is an independent distributor of PCME, Ltd. products.
 
 
7711 Welborn Street
Suite 106
Raleigh, NC  27615
 
Phone 919-790-9090
Fax 919-790-0550
 

© 2004 B3 Systems, Inc.