An overview of the OCD CM and its functions
Overview
The OCD CM Bilge Alarm unit is specifically designed for 15 ppm oily water separator units and meets the Maritime Organization's specifications for Bilge Alarm Units outlined in Resolution MEPC 60 (33).
1. PPM DISPLAY 6) ALARM 1 AJUST LED
2. SECONDS LED 7) ALARM 2 AJUST LED
3) PPM LED 8) SET/ZERO KEY
4) ALARM 1 INDICATION LED 9) UP KEY
5) ALARM 2 INDICATION LED 10) DOWN KEY
Specification
Range : 0 – 30 ppm (Trend to 40 ppm)
Accuracy : Better than IMO MEPC 60 (33) (+/- 5 ppm)
Concentration Indication : 2 x 7 segment LED
Alarm Operating Points : 1 - 15ppm (adjustable)
Alarm 1 Operating Delay : 0-20 sec (adjustable)
Alarm 2 Operating Delay : 10-240 sec (adjustable)
Alarm Contact Rating : 8A @ 240V
Alarm Relay Mode : De-energised in Alarm State
Fault Indication : Alphanumeric code
Output Signal : 0–20mA, 4–20mA (820Ω max load)
0–5V & 1–5V DC (50KΩ min load)
Projected Life (Electronics) : > 50,000 Hours
Ambient Temperature : +1°C to +55°C
Humidity : 90% RH Max @ 55°C
Sample Temperature : +1°C TO +60°C
Sample Flow : 0.5 to 2 Litre/Minute
Sample Pressure : 0.1 to 10 Bar
Clean Water Requirement : As for Sample
Weight : 2.25kg (stand-alone monitor)
7.5kg (auto-clean option)
Size : 215 x 242 x 73mm (stand-alone monitor)
290 x 468 x 76mm (auto-clean option)
Supply Voltage : 2 models available 230V/115V AC & 24V AC
Supply Variation : ±10% of Nom. Voltage
Supply Frequency : 50/60 Hz
Consumption : 10VA Max Alarm (stand-alone monitor)
: 50VA (during auto-clean cycle)
Degree of Protection : IP 55
Electrical installation (overvoltage)
classification : EN61010-1EC664 category 11
Monitor Layout
The OCD CM is split into two parts. The left side is the control module and is the user interface for the monitor. The right hand side is the measuring cell that the sample flows through to be analysed
Control side:
- Oil alarm 1 relay - User adjustable set point and delay time
- Oil alarm 2 relay - User adjustable set point and delay time
- Fault alarm relay - Changes state if an error code is displayed.
- 4-20 / 0-20 mA Output - User adjustable between 0-20mA and 4-20mA
- 0-5V Output - User adjustable between 0-5VDC and 1-5VDC
- Input voltage selector - To be set during installation, dependent on supply voltage.
- Mains Input terminals - 115VAC / 230VAC as standard. 24VAC Available.
Cell Side
The measuring cell houses the electronic and optical components for sample analysis. The sample enters through a 1/4" BSP Female inlet at the bottom and exits via a 1/4" BSP Female outlet at the top right. A knurled cap allows access to the glass tube for maintenance, which should be cleaned with a bottle brush. A front-mounted desiccator removes humidity from the sealed space containing the electronics; it uses blue or orange silica granules that need replacing annually or when they turn white, visible through a clear window.
The throttle screw is designed to restrict the outlet flow of the measuring cell. This restriction at the outlet increases the sample pressure within the measuring cell and helps to compress any small air bubbles within the sample to reduce the impact of measurement accuracy.
Calibration
To renew the calibration of an OCD CM there are two options. The complete OCD CM can be returned to Rivertrace for factory assessment and recalibration or spare calibrated parts can be purchased for replacement by the user.
The calibration for each measuring cell is stored on a small processor chip. A processor chip is supplied with each measuring cell and these must remain installed as a matched pair. If the cell is replaced without swapping the processor chip alongside, the calibration is void.
The processor chip must be installed in the display PCB within the control module. It is crucial that the chip is inserted into the chip holder in the correct orientation, identified by a "D" mark on both the processor chip and the PCB.
Once the new parts are fitted, the power to the LED within the measuring cell must be adjusted whilst clean water is within the measuring cell. We call this "Adjusting Tc (Transmission)". Full instructions on replacing the cell and chip can be found here.
It is important to remember to adjust the Tc value if the main PCB is replaced too as the power source for the LED is located on the main PCB.
Optional Extras
The main cause for failure with optical analysing equipment is fouling of the optics. As standard, a bottle brush is supplied with the OCD CM to clean the glass tube with as required. To address this issue, the OCD CM can also be supplied with an "Autoclean" system. This system automatically cleans the cell internals. The frequency of the clean is user adjustable.
We strive to meet the needs of our customer's unique applications. For this reason, we also offer this monitor as part of a bespoke system, designed around the customer, as with all Rivertrace products.
Below are some examples of bespoke items that have been included in our designs, alongside the OCD CM.
- 230VAC Mini compressor For applications requiring an Autoclean system but without compressed air availability.
- Stainless Steel mounting frame for a free-standing installation.
- SCU (Sample Conditioning Unit) for sample conditions that fall outside of our standard specification requirements.
- Sample Cooler for applications where the sample being received by the analyser is outside of our standard specification requirements.
- Vortex Enclosure Cooler for reducing the ambient temperature around the analyser in applications where extreme ambient temperatures fall outside of our standard specification requirements.
- Enclosure Heater for cold environments where freezing may cause damage.
- Stainless Steel sunshade to reduce the temperature around the analyser in exposed applications.
- Weatherproof enclosure to protect the analyser and associated equipment from severe weathers, flooding and deluge and of course acting as a mechanical protection against impact or tampering.
- Sample pressure regulators and PRVs for ensuring that the sample entering the system cannot cause damage should pressure spiking or high pressures occur.
Each bespoke system is supplied with a manual and technical drawings to support as standard and arrives to the customer as a finished product.
On-Site verification
Rivertrace offer an on-site calibration verification kit. The kit consists of two, very accurately produced samples that when poured into the measuring cell, display predetermined values. This allows the user to have confidence in the equipment.
Maintenance
Weekly
• Ensure that the monitor reads 0ppm with clean water passing the cell.
Monthly
• Check the colour of the desiccator, If the desiccator granules appear white, the desiccator will need replacing.
Yearly (units with Autoclean only)
• Replace the wiper ring on the Autoclean.
Spare Parts
RECOMMENDED SPARES
Item Qty Part Number
Desiccator packed 1 107413
Bottle brush 1 100244
Fuse (115/230 V Version) 1 106989
Fuse (24 V Version) 1 101877
Bilge Monitor Cell Cleaning Kit 1 110707
Other spares
Item Qty Part Number
Spare cell & Chip for OCD CM 1 109689
Main PCB 115/230 VAC 1 107053
Main PCB 24 VAC 1 107258
Display PCB 1 107037
Cable Gland 1 106883
Membrane Overlay 1 106847
Manual Clean Unit 1 107229
Manual/Auto Clean Wiper Ring 1 103136
Verification Water Sample Kit 1 107651