A Development of a Web-based Remote Monitoring System in the Noise and Thermal of an Enclosed Air Compressor Room

INTRODUCTION

As pointed out by the Occupational Safety and Health Act (OSHA), high noise levels can be harmful to workers and can lead to psychological and physiological ailments (Alnawafleh and Nizhibitsky, 2004; Ratnasingam et al., 2010; Mirhossaini and Pourzamani, 2008). Because of a reverberant sound propagating within an enclosed building, a noise monitoring system installed within an enclosed machine room becomes vital (Cheremisinoff and Cheremisinoff, 1977; Alley et al., 1989). To avoid noise exposure and to efficiently monitor the room’s noise level, a remote noise monitoring system installed between the machine room and the control room is necessary. In the past decade noise monitoring stations using both modem and fibre-optical communications have been established in open fields such as industrial zones, parks and roads (van den Berg, 2005; Filipponi et al., 2008; Livshitz et al., 2004; Leong and Laortanakul, 2003). However, the assessment of an indoor noise monitoring system used for entrance control has been neglected. Moreover, to prevent the breakdown of a machine caused by an inefficient ventilation system, thermo monitoring within an enclosed machine room is compulsory (Li et al., 2002). In previous works Chiu (2010a, b) monitored the temperature online in both greenhouses and multi-functional aquariums using a PC-based control system constructed with a VB interface, a sever PC and a client PC via the RS232/RS485 protocol. Other researches also utilized the PC-based control system in individual fields (Lai et al., 2010; Liandong et al., 2004; Yu et al., 2007; Amien and Lin, 2007; Yu et al., 2008). However, the sever PC located inside the room is cumbersome.

In order to reduce the working volume at the sever PC, a compact web control unit is considered. Moreover, to improve the VB interface at the client PC, an interface using a web page embedded with JavaScript (Lou et al., 2003; Huang and Tseng, 2002; Mahdavi et al., 2008) is adopted. In this paper, a web-based temperature and sound monitoring system for an enclosed air compressor room shown in Fig. 1 is introduced. Here, the web-based interface is established using a web page embedded with JavaScript.

Fig. 1(a-b):	Remote/near ports for the sound and thermal monitoring system within an air compressor room. (a) Air compressor room equipped with a sound level meter, a thermocouple and web control unit and (b) Remote PC (client PC)

A compact web control unit installed inside the air compressor room is linked with a sound level meter (Fig. 2) and a k-type thermocouple. The current and historical temperature and sound data will be remotely monitored. Therefore, the security of the system and the status of the worker’s hearing can be assured.

A WEB-BASED SOUND AND TEMPERATURE MONITORING SYSTEM

An automation system used in industrial, agricultural and aquatic environments to reduce manpower is customary.

Fig. 2:	A multi-function sound-level-meter installed within an air compressor room

Fig. 3:	An ADAM4118 module with eight channels

As indicated in Fig. 1, to protect the hearing of workers and avoid overheating within the air compressor, a web-based interface is established using a web page embedded with Javascript. Here, an ADAM4118 module shown in Fig. 3 is inputted with analogue signals emitted from the sound level meter and the thermocouple. Because there is a serious decay of the signal for a RS232 protocol traveling over a long distance (fifteen meters), a new protocol (RS485) with a steady signal transmission is recommended. Therefore, the ADAM4118 that transforms analogue signals to digital signals will be used to forward the signals to the web control unit via the RS232/RS485 module. Also, the web control unit connected to the Ethernet will save the digital data and forward the data to the web page. The real-time data transmitted to the web page will be updated online. Moreover, a default setting of the web control unit will save the digital data in a Comma Separated Value (CSV) format every ten minutes.

As indicated in Fig. 4, the analogue signals received from the sound level meter and the thermocouple are transformed to digital signals by the AD converter within the ADAM4118 module. The digital data will be transmitted to the web control unit controller using a RS485 protocol.

Fig. 4:	Hardware for a web-base monitoring system

Fig. 5:	The setting for the web page driver

Also, the data will be continuously saved on the web control unit in a CSV format. The related temperature and noise level will be dynamically monitored and displayed in the remote PC using a web page embedded with JavaScript. As indicated in Fig. 3, there are eight channels that are available to use sensors.

The web control unit can trigger the web page, demonstrate the profile elements and download the signal data via the File Transfer Protocol (FTP). The remote PC can be linked with the web control unit when both the PC and the web control unit have the same IP address. The setting for the web page driver is depicted in Fig. 5. The digital data of the sound and temperature will be periodically recorded on the web control unit with a default file-saving name from 1 to 31 (REC01.CSV to REC31.CSV 31).

Fig. 6:	The output excel file downloaded by the PC using the FTP protocol

Fig. 7:	The structure design of the HTML/JavaScript

As indicated in Fig. 6, the data can be recalled by the FTP and shown in an excel file.

The structure design of the web page in HTML/JavaScript is shown in Fig. 7. The flow chart for the signal reading procedure within an embedded web page is depicted in Fig. 8.

As indicated in Fig. 9, the monitoring interface for sound and temperature transmitted from an air compressor room can be plotted using a time trend diagram.

Fig. 8:	Flow chart for the signal reading procedure within an embedded web page

Fig. 9:	The monitoring interface for sound and temperature transmitted from an air compressor room (at the beginning of the web page without being triggered)

Various lights and alarms will be triggered when either the sound or the temperature is in an abnormal condition (i.e., beyond the specified limit).