MARKLAND SPECIALTY ENGINEERING LTD.

MARKLAND SPECIALTY ENGINEERING LTD. MARKLAND SPECIALTY ENGINEERING LTD.

Please review the following, and if you need further technical assistance,
send us details of your specific application.

HOW   IT   WORKS
      A vertical Probe, submerged in the tank, contains 64 infrared high intensity Light Emitting Diodes stacked vertically, which shine horizontally across a probe gap to 64 Phototransistor detectors. This gap contains either liquid or sludge. See the cross section of the "Probe Active Element" illustrated above, which shows one of the LED/Phototransistor pairs. The 64 pairs are sequentially scanned by a microcontroller to locate the sludge bed. Beam power intensity is automatically adjusted to accommodate different sludge and overlying liquid concentrations. At its highest power level the beam will shoot through your hand, you could count the bones, but there is no hazard since the beam is only on for a few microseconds. This high intensity beam easily penetrates fouling on the probe's windows, and as long as the solids in the probe gap are high relative to the solids in the scum layers on the windows, the meter continues to read correctly. Eventually, the probe has to be removed and washed.

PROCESS   CONTROL
      A desludge pump can be operated automatically from the Low Set-Point Relay along with a Pump Run Interval Timer, and the High Set-Point used as an alarm for excessive sludge depth. Alternatively, the desludge pump can be turned ON at the High Set-Point and OFF at the Low Set-Point, or the 4-20 ma output can be used for continuous variable speed drawoff. Either the 4-20 ma or the RS-232 and optional RS-485 can link the meter to your computer for centralized process control.

PAUSE   SWITCH   USES
      An externally located switch with a pair of Normally Open contacts, can be connected to act as a "Pause Switch". When these contacts close, the Markland meter freezes its last reading, and the LCD displays "METER DISABLED HOLDING LAST READING". This feature is used for a batch mix process to disable the meter during mixing. It is also used to lock out the meter when the probe is tipped up by a traveling scraper. Both of these uses are illustrated above. When the pause switch reopens its contacts, the meter waits 30 seconds for the sludge to settle down before resuming normal operation.

USES   AND   ADVANTAGES
      Automatic desludging yields thicker sludge than Timers or manual methods, and reduces sludge disposal or processing cost. Plants that are not staffed 7 days, 24 hours, rely on automatic desludging to maintain proper sludge blanket levels when unstaffed. The 602 Series can be used as a 'stand alone' system to alarm or automatically control a pump, or, it can be an intelligent sensor for a PLC or computer. The optional settled sludge profile viewable on your computer screen, can be helpful during plant upset and assist in proper coagulant dosage control. The meter is used in sewage and drinking water plants, mine ore processing, metal hydroxide sludge blanket level control, industrial process water and wastewater clarification, or wherever solids are separated from liquids.

INTELLIGENT   MICROCONTROLLER
      The microcontroller scans the probe elements and locates the sludge bed if there is one, and displays this on the LCD. Any top or bottom offset is automatically incorporated into the reading. Out of range, or zero readings are displayed if there is no sludge/liquid interface. Error trap routines identify and reject bad scans. To lessen the impact of short term events such as passing 'clouds', the Meter accumulates a running average of several good scans, which dampens the response and smooths the output. If after several attempts, the Meter can not obtain good scan data (i.e. broken wire, etc.) the LCD reads "SIGNAL LOST"; both Relays are de-energized; and the 4-20 ma output goes to zero indicating fault. During a fault condition, the Meter continues trying to find good scans and resumes normal operation as soon as good data is obtained. Automatic intensity control adjusts the LED firing power to the correct level for each particular sludge/liquid. Progressive slime buildup on the probe merely results in the instrument boosting its beam power level to the intensity required to shoot through the scum. An advanced self-diagnostic routine permits display of problems right on the Meter's LCD, or, these can be downloaded on the serial link to a user's computer. If site-specific problems require an adjustment of the algorithm, the software can be reprogrammed using the front panel membrane switch.

ADVANCED   SELF-DIAGNOSTICS
      Markland's advanced self-diagnostics assist the user in three ways:

Pressing the "Self-Diagnostic" key on the front panel calls in an instrument check which is displayed on the LCD.
Markland's engineering department can be contacted at Fax (416) 244-2287 to assist with stubborn field problems.
For more complex site-specific process problems that require a history, Markland will supply our unique self-diagnostic memory module that plugs into the meter to record the meter's function over time. When the module is returned, Markland can run your meter at the factory to diagnose difficult site problems and recommend solutions.

There is No Charge for this engineering support. Markland instrumentation is carefully designed and manufactured to function in all industrial environments. If site problems develop, our advanced diagnostics will help resolve the difficulties quickly.

SET-POINT   RELAYS
      Two independent set-points (High & Low) are standard. In order to ignore short term transient sludge 'clouds', the actual depth must exceed the set-point for 30 seconds continuously, before the Relay energizes. Similarly, there is a 10 second delay which also must be continuous before the Relay will de-energize. Set-points are entered through the front panel membrane switch and are locked into EEPROM memory, which indefinitely retains the set-point, even during power failure, without requiring backup batteries. The LCD displays the current set-points, which are easily changed using the membrane switch.

OTHER   MARKLAND   SYSTEMS
      Markland's portable sludge level detector, the SLUDGE GUN®, is a valuable operating tool for manual sludge bed detection. Markland also manufactures Suspended Solids Meters that use ultrasonic attenuation to measure concentration in sludges and slurries that are too thick for optical methods. Markland DUCKBILL® wastewater Samplers operate without mechanical moving parts for reduced maintenance and high reliability. Fax your letterhead for a complete catalog of Markland products.

SPECIFICATIONS

Materials

Probe - PVC
Mast - PVC Pipe
Clamp - Stainless Steel & Polypropylene
Cable - Vinyl Jacketed
Enclosure - Fiberglass Body & Clear Plastic Cover

Dimensions

Probe:

Overall Length 1330 mm (52¼ in.)
Active Element Length 1219 mm (48 in.)
Cross Section 64 mm (2½ in.) x 38 mm (1½ in.)
Gap - 25 mm (1 in.)
Mast - 3½ meters (12ft.), 1 in. Sch. 80, shipped in 3 pieces with fittings

Enclosure: Width 343 mm (13½") · Height 229 mm (9") · Depth 200 mm (77/8")

Cable Length

15 meters (50 ft.) pigtail supplied (measured from top of Probe). Maximum cable length 150 meters (500 ft).
Order extra cable separately if pigtail length not sufficient

Active Element Spacing

64 pairs infrared LED/Phototransistor, spaced vertically on 19 mm (¾ in.) centers. Dual Model has 128 pairs

Accuracy

± 2cm (± 1 in.)

Bottom Offset

Adjustable, 0-700 cm or in. (NOTE: For '-DAF' & '-UD' types this is Top Offset)

Depth Units

Selectable, inches or centimeters

Temperature

Maximum 50°C (120°F)

Power

110/220 VAC, 220/240 VAC, 50/60 Hz (advise with order). 10 watts

Outputs

· Liquid Crystal display (LCD) 2x20 Digit Alphanumeric
· 4 - 20 ma output signal, linear with sludge depth
· Two DPDT, 5 Amp, Relays, independently adjustable set-points
· RS - 232 Serial Port
· RS - 485 Serial Port (Optional)

Models

602	Reads sludge depth UP from tank bottom
602 - UD	Reads sludge blanket location DOWN from liquid surface
602 - DAF	Reads sludge/liquid interface in Dissolved Air Flotation thickeners
602 - LP	Special model for Drinking Water Plant upflow clarifiers where overlying water is very clear & sludge is thin (consult factory for further details)
602 DUAL & 602-DUAL-UD	Uses 2 probes, one mounted 48 in. (122 cm) above the other to give 96 in. (244 cm) continous span

Approvals

CSA Approved and CE Conformance

To receive a FREE engineering recommendation along with a quote, please phone or FAX
us with the technical details about your application and your mailing address.
If you prefer, fill out the email online request form found below.

CLICK HERE TO FILL OUT THE ONLINE REQUEST FORM.
http://www.sludgecontrols.com/602_specific.html

48 SHAFT ROAD, REXDALE (TORONTO), ONTARIO, CANADA M9W 4M2
Phone: (416) 244-4980		Fax: (416) 244-2287
E-mail: markland@sludgecontrols.com Website: www.sludgecontrols.com