T&L Scanning Probes - DOP Solutions

T probes and L probes for scan testing
Safe-Change Housings and difficult-to-access HEPA filters
Safe-change (bag-in-bag-out) housings have traditionally been tested volumetrically for
leakage. In some cases this may be an acceptable measurement. The volumetric test
though is 300-3000 times less sensitive than the ISO14644-3 scan test. There may be
substantial defects in a HEPA filter installation that will pass the DOP volumetric test.
This could significantly compromise human safety or the environment.
To allow a scan test for filters which cannot be accessed or conventionally scanned
DOP Solutions have produced new scanning options, T or L probes.
A T scanning probe is a permanent installation forming part of the filter housing, and is
installed at point of manufacture usually, but can be retrofitted. It is positioned into the
downstream (clean side) of the filter housing, sealed through a glanded port and guided
on rails across the filter. The probe shaft extends out of the filter housing and is sealed
when not in use. The sample probe is sealed to the housing and the aerosol photometer
downstream sample tube is attached to the probe shaft.
Scanning of the filter is accomplished by drawing the probe across the filter or scanning
zone at 1.5 cm per second. High differential pressures may require an additional return
sample port in the safe-change housing, which also ensures the sample air is discharged
safely back into the system that it was taken from.
The T Probe comprises a 316 stainless steel with graduated sample holes, stainless
steel probe sealing cap, stainless steel upstream sample return port and fittings for
connecting it within the filter unit.
Detailed installation instructions are provided with the sample probe kit and it is a
requirement of the purchaser to install the component parts into the housing correctly.
Each sample probe is manufactured to fit into the housing according to the dimensions
supplied. The sample probe cap and sample return port are normally welded to the
housing at the appropriate place but the system may be retrofitted simply by drilling port
holes in the appropriate position and sealing the securing nuts with silicone compound.
Retrofit kits are available.
These are not intended, nor should they be used, to replace the conventional filter
scanning probe with a photometer in the interests of time saving. This test is more
reliable than the volumetric method, but the scanning speed must be slower than that for
conventional testing, and the result will only indicate the presence of a leak but not the
exact location of where it is.
T & L probes v6
PRODUCT
T probe
L probe
MODEL
NUMBERS
DOP610-RF
DOP610-W
DOP305-RF
DOP305-W
DOP-315-L
DOP-L
DOP SOLUTIONS LTD
Unit 10
Protea Way
Pixmore Avenue
Letchworth
Hertfordshire
SG6 1JT
United Kingdom
Telephone:
+44 (0)1462 676446
Facsimile
+44 (0)1462 486078
Email:
sales@dopsolutions.com
Web:
www.dopsolutions.com

L probe Sample port ABS 3/4in capped 105 x
44mm, 50 mm high. Part No. : 630-SP-34IN-12
Alternative
L probe Sample port ABS 3/4in capped 105mm diameter,
50 mm high. Part No.: 630-SP-34IN
Demonstration view of “L” Probe and Sparge pipe
ORDERING INFORMATION
DOP610-RF-920-12 T probe for mechanical installation
into 610 x 610mm filter housings.
DOP610-W-920-12 T probe for welded installation into
610 x 610mm filter housings.
DOP305-RF-449-12 T probe for mechanical installation
into 305 x 305mm filter housings.
DOP305-W-449-12 T probe for welded installation into
305 x 305mm filter housings.
Typical HEPA Filter Safe-Change
Housing into which the Longitudinal
Scanning Probe may be installed.
“L” Scanning Probes
“L” Probe with port attachment
Part No. :DOP-315-L-1000
“L” probe is designed for scanning safe change HEPA
filter housings, and any other inaccessible filter with
dimensions of 610x610mm.Shaft length of 1.0 metre
will allow deeper filter areas to be scanned. The probe
handle is manufactured in brass tube & the left and
right hand scanning arms from aluminium.
The scanning section (90 degrees to the main tube
shaft) has graduated holes to ensure linear airflow into
the scanning probe over the measuring distance of
315mm.
This scanning probe is supplied with the 630-SP-34IN-
8MM scanning probe tube adaptor as standard. To be
used with the 630-SP-34IN sample port.
Where longer lengths of scan are required use the
DOP-L-SCAN probe. This is a modular scanning probe
kit with multiple length 1/2” shafts for scanning filter
systems where the long shaft of the DOP-315-L-1000
probe prevents access to the scanning ports.
Unit 10, Protea Way, Pixmore Avenue, Letchworth, Herts, SG6 1JT Telephone: +44 (0) 1462 676446 Facsimile: +44 (0) 1462 486078
Email: sales@dopsolutions.com Web: www.dopsolutions.com