Murco MGS Manual de usuario descargar pdf (Pagina 2)

11-- IINNTTRROODDUUCCTTIIOONN

The frequency and nature of testing or calibration may be determined by local

regulation or standards.

EN378 and the FGAS Regulation require an annual check in accordance with

the manufacturer’s recommendation.

Murco recommends annual checks by bump test, and gas calibration

on site at two yearly intervals in the case of semiconductor SC sensors

and infrared IR sensors with sensor replacement every five years or as

required. In the case of electrochemical EC sensors we recommend

annual bump test and sensor replacement at two yearly intervals and

gas calibration. This should eliminate end of life concerns, and

constantly renew the detection system.

If the MGS is exposed to a large leak it should be tested to ensure correct

functionality by electrically resetting the zero setting and carrying out a

bump test, see procedures below.

There are two concepts that need to be differentiated: bump test and

calibration

Bump Test

: This consists of exposing the sensor to a gas and observing its

response to the gas. The objective is to establish if the sensor is reacting to

the gas and all the sensor outputs are working correctly. There are two types

of bump test.

Quantified

: where a known concentration of gas is used, or

Non-Quantified: where a gas of unknown concentration is used.

Calibration

: This consists of exposing the sensor to a calibration gas, setting the

“zero” or “Standby voltage”, the span / range, and checking/adjusting all the

outputs, to ensure that they are activated at the specified gas concentration.

Procedures for bump test and calibration vary depending on the sensor

technology used and the gas in question. The MGS is available in three sensor

versions: Semiconductor (

SSCC

), and Electrochemical (

EECC)) aanndd iinnffrraarreedd ((IIRR))

Before you carry out the test or calibration:

1- Advise occupants, plant operators, and supervisors.

2- Check if the MGS is connected to external systems such

as sprinkler systems, plant shut down, external sirens

and beacons, ventilation, etc. and disconnect as

instructed by the customer.

3- Deactivate alarm delays if selected at JP5, JP6 as per

instructions in Diagram 1.

4- For Bump Test or Calibration the MGS should be

powered up overnight. If the unit has been installed and

running for about 24 hrs, and you need to power it off

for a short time to set the delay at 0 min, then the

normalisation period is about 5 min (this is indicated by

the green LED flashing) and then you can begin the

testing or calibration. If sensors have been in long-term

storage or the detectors have been turned off for a long

time, normalisation would be much slower. However

within 1-2 hours the sensor should have dropped below

the alarm setting and be operational. You can monitor

normalisation progress exactly by monitoring the

sensor output, on CON 2 between pins OV & VS.

See Section 5.

22-- BBUUMMPP TTEESSTT ((eevveerryy yyeeaarr))

Ideally bump tests are conducted on site

in a clean air atmosphere.

Prior to carrying out a bump test, check

and adjust the zero setting as described

in the Calibration section page 3 -

Sensor PCB 1.1 and 2.2.

2.1 Semiconductor and IR sensors for

hydrocarbons: We offer cylinders of

gas at known concentrations for

quantified tests. This consists of

exposing the sensor to the gas and

checking that alarm lights and relays

are activated. If this is not available,

for a non-quantified test you can use

a gas cigarette lighter. By cracking

open the valve without igniting the

gas, you release the gas onto the

sensor and force it into alarm. Check

that alarm light, sounder and relay

are activated.

2.2 Electrochemical sensors: We offer Ampoules of ammonia (NH3) at 100ppm

and 1.000 ppm. Cylinders of calibration gas are also available. These are a

quantified test. For details of other Ampoules, please contact us.

2.3 Infrared sensor for CO2: We offer Ampoules of CO2 at 5000 ppm.

Cylinders of calibration gas are also available. These are a quantified test. If

these are not available, then you can breathe on the sensor. Human breath

has enough CO2 to trigger the alarm. This is a non-quantified test.

2.4 Bump test using gas ampoules:

1- Make sure that both the ampoules and the

calibration beaker are clean and dry.

2- Unscrew the beaker hold screw and place

the ampoule so that is sits in the

base of the beaker. As per

illustration.

3- Tighten on the screw

ampoule without breaking it.

4- Remove the enclosure lid of

the gas detector (not in Ex area).

5- Connect voltmeter to monitor sensor response, monitor 0-

10v (Jumper JP1 and JP3 off) response on CON 2

between pins OV & V.

6- Place the beaker over the sensor head using the multi

sensor adaptor to fit the sensor, or, if an Exd, IP66 or

Remote sensor head version, screw the beaker on the

remote sensor head M42 thread, or M35 thread adaptor. It

should be as tight fitting as possible to allow maximum

exposure to the gas.

Flexible non-

absorbant

tubing

Flow

Regulator

Typical Flow

0.3L/Min

Outlet 5/8’’

18 UNF

(C10)

Cylinder

360mm high x 88mm diameter

440mm high with flow regulator

110L capacity of calibration gas

Weight 1.4 kg

ented

Calibration

Hood

Calibration Kit

COM

Relay

+ Sounder

ZeroSpan

SW2 SW1

LD2 LD1

CN1 CN2 CN3

JP6

JP1

Relay & Sounder Delay – JP5 & JP6 off : no delay

JP5 on only : 1 Minute

JP6 on only : 5 Minutes

JP5 & JP6 on : 10 Minutes

JP3 – on : 4-20mA or 2-10Volt output

off : 0-10Volt or 0-5 Volt output

JP2 – on : Sounder enabled

JP1 – on : 0-5Volt output

off : 0-10Volt output

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