Sierra Monitor Corporation 2400-01, 2400-21, 2404-00 Instruction Manual

Sierra Monitor Corporation

1991 Tarob Court, Milpitas, CA 95035

[phone]
[phone]

VAULT GAS MONITOR

Model 2400-01
Model 2400-21

SMOKE DETECTOR OPTION

MODEL 2404-00

APPLICABILITY & EFFECTIVITY

This manual provides instructions for the following Sierra Monitor products:
Model

2400-01 Vault Gas Monitor
2400-21 Vault Gas Monitor, Low CO
2404-00 Smoke Detector for 2400

The instructions are effective for the above models as of October 1, 1996

Description

Instruction Manual Part Number: T10007

Rev. B1

Instruction Manual

SECTION

1. PRODUCT DESCRIPTION 1

1.1 Introduction 1

1.2 General Description 1

1.2.1. Mechanical 1

1.2.2. Uninterrupted Power Supply 1

1.2.3. Alarm Relays 2

1.2.4. Alarm Indicators 2

1.2.5. Test Switches 2

2. INSTALLATION 3

2.1 Unpacking and Inspection 3

2.2 Installation & Set-Up 3

2.2.1. Enclosure Mounting 3

2.2.2. External Connections 3

2.2.3. Start-Up 3

3. OPERATION 4

3.1 Status Indication 4

3.2 Function Tests 4

4. CALIBRATION 5

4.1 Frequency of Calibration 5

4.2 Calibration Procedure 5

4.3 Maintenance 5

5. INFORMATION TO INSTALLERS 6

5.1 Discussion & Background 6

5.2 Electrical Adjustments 6

6. SMOKE DETECTOR 8

6.1 Product Description 8

6.2 Installation 8

6.3 Operation 8

7. NICKEL CADMIUM BATERIES 9

7.1 Nickel Cadmium Battery Operation 9

8. SPECIFICATIONS 10

9. PART NUMBERS & SPARE PARTS LIST 11

APPENDIX: Figures 1 thru 6

PAGE

TABLE OF CONTENTS

Table of Contents

Instruction Manual

1. PRODUCT DESCRIPTION

1. PRODUCT DESCRIPTION

1.1 INTRODUCTION

The Model 2400 series Vault Gas Monitors
provide continuous monitoring of Methane
(and other Combustibles) and Carbon
Monoxide gas simultaneously in a confined
space to provide safety for personnel and to
reduce the hazard of gas explosion. Two
versions of the Model 2400 are available.
The 2400-01 has a Carbon Monoxide
sensor with a range of 50-200 ppm CO.
The Low CO version, 2400-21, has a range
of 0-100 ppm CO for current OSHA and
NIOSH regulations with the Model 2400.

Features of the Model 2400 series products
include:

- Local visual and audible alarms.

- Remote Visual Alarm Indication Box
(Model 2401 option)

- Ambient temperature change
compensation.

- Long-life solid state gas and
temperature sensors.

- Battery back-up for uninterrupted
power supply.

- Continuous battery voltage monitoring.

- RFI/EMI AC Power Line Filter
together with electrical and mechanical
design to reduce electro-magnetic
interference.

- Five alarm relay contacts.

- User selectable active or passive relay
alarm test.

- Single PC board assembly and modular
harness construction for easy
maintenance.

- Alarm Test button

- Mil Spec Amphenol connectors for AC
and alarm lines.

- Smoke Detector (Model 2404-00
option) with battery back-up.

- Fused Battery Charging Circuit.

- Fused Vent Relay (K3).

1.2 GENERAL DESCRIPTION

1.2.1. MECHANICAL

The Model 2400 is housed in a NEMA
3 type hinged enclosure with the input
power connector, relay output
connector and sensors accessible on
the sides and bottom.

SENSORS:

Three sensors are mounted on the
bottom of the enclosure. This
orientation provides protection

from dust and moisture
contamination. The sensors can
easily be replaced without removal
of the monitor from its permanent
mounting. Two of these sensors
are for gas detection and the third
contains two separate
thermocouple devices to permit
direct measurement of ambient
temperature. The Combustible and
Carbon Monoxide sensors are
metal-oxide semiconductor type
solid state devices for long life.
The electrical resistance of the
sensors is inversely proportional
to the gas concentration.

CARBON MONOXIDE: This
sensor is specifically designed to
detect carbon monoxide gas. The
2400-01 has a metal-oxide
semiconductor type solid state
sensor for long life with a
calibration range between 50 ppm
and 200 ppm. The 2400-21 has an
electrochemical type sensor with a
calibration range between 10 ppm
and 100 ppm. The sensors are
relatively insensitive to methane.

METHANE: This metal oxide
semiconductor type solid state
sensor is designed to detect
methane gas and other explosive
gases. The calibration range is
between 5% and 25% of LEL for
methane. The sensor is relatively
insensitive to CO.

TEMPERATURE: Each
semiconductor type sensor is
compensated for variations of
ambient temperature over a range
of 0 to 40oC.

CONNECTORS:

Mil-Spec Amphenol connectors
are used for the relay and remote
indicator outputs and for the
power input to provide
compatibility with vault hardware
specifications.

1.2.2. UNINTERRUPTED POWER
SUPPLY (UPS)

The AC/DC power supply is factory
configured for 120 VAC (60 Hz)
operation. An EMI/RFI Line Filter is
provided to filter the AC power line
from high frequency noise. The power

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Instruction Manual

supply includes a built-in constant
current Ni-Cad battery charger with up
to one ampere capacity. Batteries can
be fully charged in 14 hours. The six
"D" size NiCad pack batteries will
provide up to nine hours back-up. A 5
volt 0.5 Amp regulator supplies power
to the analog and digital sections. The
battery voltage is constantly monitored
and if it fails, a low battery voltage
signal is generated. The UPS and DC
electronics are electronically protected
against short circuits.

1.2.3. ALARM RELAYS

There are five alarm relays. All are
single-pole double-throw with 6 amp
dry non-inductive contacts at 120/240
volts AC.

FAILURE RELAY: The failure relay
is activated when either gas sensor
becomes defective (open sensor
resistance or no heater voltage). The
failure relay is also activated if both
the AC and battery back-up power
supplies fail.

CARBON MONOXIDE RELAY:
The Carbon Monoxide Relay is
activated when the concentration
exceeds the calibrated threshold setting
(100 ppm CO on the 2400-01 and 25
ppm CO on the 2400-21).

COMBUSTIBLE RELAY: The
Methane Relay is activated when the
concentration of Methane exceeds the
calibrated threshold setting (5000 ppm
CH4).

VENTILATION RELAY: The
Ventilation Relay is activated when
either the CO or CH4 gas
concentration exceed their calibration
levels. The common contact of the
ventilation relay is fused with a 4 amp
socketed micro-fuse.

REMOTE INDICATOR RELAY:
The Remote Indicator Relay is
activated when either the Failure Relay
or the Ventilation Relay is activated.
Any of the following conditions will
activate the Remote Indicator Relay
which is normally connected to the
Remote Indicator box:

* Excess Carbon Monoxide
* Excess Methane
* AC and Battery Failure
* Carbon Monoxide sensor

1.2.4. ALARM INDICATORS

The front panel has one audible alarm,
eight annunciator lights and one test
button.

AUDIBLE ALARM: The Audible
Alarm will sound when either the CO
or CH4 gas concentration exceeds the
respective calibrated threshold levels.
The Audible Alarm produces a
continuous tone of 2900 Hz at 68 dB.

POWER FAILURE ALARM: The
Power Failure Alarm consists of two
lamps; a Power-On Lamp (green) and
a Low Battery Indicator (red). The
Power-On indicates that the +5 VDC
and 8.2 VDC supplies are present. The
Low Battery indicator is activated
when the battery voltage drops below
+6.2 VDC.

CARBON MONOXIDE STATUS
LIGHTS: The three CO status lights

are: Safe (green), Alarm (red) and
Sensor Failure (red).

COMBUSTIBLE STATUS
LIGHTS: The three Combustible

status lights are: Safe (green), Alarm
(red) and Sensor Failure (red).

1.2.5. TEST SWITCHES

Two test switches are provided to
allow functional testing of the monitor
outputs:

GENERAL TEST: A momentary
push button is provided on the front
panel for testing the operation of all
lamps, three relays (Ventilation,
Combustible gas, and Carbon
Monoxide gas) and the Audible Alarm.
A slide switch is located on the
electronics board to enable or disable
the relay portion of this test. In the up
position (ON), the test will be active.
In the down position (OFF), the test
will be passive. (This switch (SW1) is
located on the left hand side of the
circuit board.

FAILED SENSOR TEST: An
auxiliary momentary push button test
switch (SW3), located in the bottom
right hand corner of the circuit board,
is provided for testing the Failure and
Remote Indication relays and the
Sensor Failure lamps by simulating a
sensor failure.

failure
* Methane sensor failure.

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Instruction Manual

2. INSTALLATION

2.1 UNPACKING AND INSPECTION

Remove the instrument from its packing
container and inspect to insure that all
items listed on the packing slip have been
received in good condition.

Open the door by loosening the two screw
clamps. Inspect the internal electronics and
wire harnessing to insure that no damage
has occurred during shipment. The battery
pack connector located above the door
hinge is shipped disconnected and should
be left open until the monitor is ready to be
turned on.

2.2 INSTALLATION AND SET-UP

2.2.1. ENCLOSURE MOUNTING

Mount the enclosure in the selected
location by bolting the top and bottom
flanges to a vertical surface.

2.2.2. EXTERNAL CONNECTIONS
A.C. POWER PLUG: Connect the

three pin amphenol plug to the main
(user supplied) AC power cord. Refer
to Figure 1 for pin configuration.

ALARM RELAY PLUG: Connect
the 24 pin amphenol connector plug to
the required (user supplied) signal,
light or fan activation lines. Refer to
Figure 1 for pin configuration.

2.2.3. START-UP
POWER ON: Connect the three pin

power plug to the receptacle on the
upper left side of the enclosure. After
a short pause the audible alarm will
sound (on the Model 2400- c21, only
the combustible alarm will sound), the
alarm lights will light on the front
panel and the calibration lights inside
the enclosure will light. The alarms
will stabilize within five minutes at
which time the audible will cease and
the "safe" lights on the front panel will
light.

CONNECT BATTERY PACK:
Connect the mating parts of the battery
pack connector to enable the battery
back-up and begin the continuous
charging of the batteries. (Initial
charge may be low).

MONITOR STABILIZATION: To
avoid false alarms during the sensor

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stabilization period and to fully charge
the battery pack, allow twenty four
hours before connecting the alarm
outputs.

ALARM CONNECTION: Connect
the twenty four pin connector to the
receptacle on the lower left side of the
enclosure.

Instruction Manual

3. OPERATION INSTRUCTIONS

The Model 2400 requires no operator
intervention except for periodic calibration.
The following information can be followed
to insure that the initial installation is
correct and to insure that the external
wiring is correct.

3.1 STATUS INDICATION

Table 1 describes status of each indicator
under various conditions:

3.2 FUNCTION TESTS

The following function tests can be
performed to confirm the conditions
described in Table 1.

TEST LIGHTS: Press the "Test Lights"
button and check that all panel lights turn
"ON" and that
the audible alarm turns on. If the "active "
relay test is used the carbon monoxide,
combustible and vent relays will activate
during this test.

FUNCTION TEST: Apply gas from a
cigarette lighter (WITHOUT FLAME) or
other high concentration source to the CH4
sensor and check that the Combustible
Alarm light goes on.

BATTERY BACK-UP TEST:
Disconnect main AC and check that
monitor still functions to confirm that the
batteries are charged and functional.

SENSOR FAILURE TEST: Open door
of enclosure and remove either sensor
connector from the receptacle on the board
and check front panel for a sensor failure
alarm. (NOTE: To remove the sensor
connector grip the connector housing with
pliers - do not pull the wires)

CONDITION LIGHTS RELAYS AUDIBLE

SYSTEM CO METHANE
POWER BATT SAFE ALM. FAIL SAFE ALM. FAIL CO CH4 FAIL VENT REMOTE
AC ON

SAFE ON ON ON
CO ALARM ON ON ON ON ON ON ON
CH4 ALARM ON ON ON ON ON ON ON
CO FAIL ON ON ON ON ON
CH4 FAIL ON ON ON ON ON
LOW BATT ON ON ON ON ON ON

AC OFF

BATT OK ON <--------------- SAME AS ABOVE ------------------------->
BATT LOW <---------------- SAME AS ABOVE ------------------------> ON ON
BATT DEAD

TEST LIGHTS

ACTIVE ON ON ON ON ON ON ON ON ON ON ON ON
PASSIVE ON ON ON ON ON ON ON ON ON

TABLE 1

STATUS INDICATORS

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Instruction Manual

4. CALIBRATION INSTRUCTIONS

4.1 FREQUENCY OF CALIBRATION

The manufacturer recommends that the
Model 2400 be calibrated every 180 days.

4.2 PROCEDURE
PREPARATION: Open the door of the

enclosure and locate the two adjusting
potentiometers which are immediately
above the connectors for the two gas
sensors. Adjustment of these
potentiometers raises and lowers the
sensitivity of the respective gas sensor.
Also locate the two LED indicators near the
respective potentiometers. The LED on the
left is the carbon monoxide calibration
indicator, the LED on the right is the
combustible calibration indicator.

CALIBRATION - METHANE: Apply
5000 ppm methane calibration gas at 50
cc/minute to the combustible sensor and
watch for the calibration indicator to turn
on. If the indicator turns on within five
seconds of application of the gas and turns
off within five seconds of removal of the
gas the sensor is correctly calibrated. If the
indicator fails to turn on keep the gas on
the sensor and adjust the potentiometer
clockwise until the calibration indicator
turns on. If the indicator turns on too
quickly and stays on for too long after
removal of the gas adjust the potentiometer
counter-clockwise to decrease the
sensitivity and repeat the calibration
process.

CALIBRATION - CARBON
MONOXIDE: Apply carbon monoxide

calibration gas to the CO sensor.
Calibration gas for the 2400-01 is 100 ppm
CO at 50 cc/minute and for the 2400-21 use
25 ppm CO (factory standard), or 35 ppm
at 100 cc/minute. Watch for the calibration
indicator to turn on. If the indicator turns
on within one minute of application of the
calibration gas (within two minutes for the
2400-21) and turns off within one minute
after removal of the calibration gas (within
two minutes for the 2400-21) the sensor is
correctly calibrated. Adjust the sensitivity
as described in the preceeding paragraph.

NOTE: Sierra Monitor Corporation
recommends using the Model 26 Gas
Sensor Calibrator, Model 1200-26.

4.3 MAINTENANCE

Except for periodic calibration as described
above, no routine maintenance is required.
The following items may require
replacement due to age and deterioration:

SENSOR: Unplug the failed sensor by
grasping the top of the white plastic
connector housing (use pliers). (Do not
grasp the bottom of the housing which is
permanently attached to the circuit board.)
Pull firmly to unplug the sensor. Remove
the large nut which holds the sensor in the
enclosure frame. Discard the old sensor
and replace by reversing these directions.
With the semiconductor sensors allow the
new sensor to stabilize for at least one day
and re-calibrate. The electrochemical
sensor on the 2400-21 will stabilize in less
than one hour.

BATTERY PACK: Disconnect the
battery harness at the in-line connector on
the battery pack. Cut two large "ty-wraps"
and lift out the battery pack. Install the
new battery pack. Use new "ty-wraps to
secure the pack. Plug in the connector.

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