Akira Ogura, Research & Development Department, Fluid Technologies Unit

Introduction

The Nikkiso E Monitor is designed for mounting onto Nikkiso Non-seal Pumps, and over 30,000 units have been sold since it was placed on the market more than a decade ago. This success may be attributed to the functions of the E Monitor, which filled the need for a facility diagnostic technology that could predict maintenance times–-with the added benefit of improving reliability.
At the same time, the spread of preventive maintenance trends and the subsequent increase in the amount of data that needs to be managed have forced more and more companies to seek integrated management (systemization) solutions. To answer these needs, Nikkiso developed the E Monitor system, detailed in the following paragraphs.

Nikkiso E Monitor

The Nikkiso Non-seal Pump has an enclosed motor and pump integrated into a single housing. Because it uses no shaft seals, there are no fluid leaks. However, because the bearings are inside the motor, bearing wear cannot be checked easily from the outside, making it difficult to determine when to replace the bearings.
For these reasons, the Nikkiso E Monitor (also known as the field type E Monitor) was developed to accurately and easily monitor bearing wear in both the radial and axial directions of the bearings (Figure 1).
Bearing wear is indicated by the number of lit LED bars. By occasionally checking these LED bars, anyone can see changes and the trends for bearing wear. It is then possible to predict how long the bearings will last, making it easy to determine the right time for replacement, previously considered hard to do.

Figure 1: Structure of Nikkiso Non-Seal Pump and Nikkiso E Monitor

Monitoring Bearing Wear

1.On-site monitoring

The most common monitoring method requires maintenance staff to check the number of LED bars lit on the field type E Monitor at the locations where pumps are installed during routine checks (as a form of trend monitoring).

2.Remote monitoring

As the field type E Monitor is built into the pump, wear must be checked at the pump. To cut maintenance costs, Nikkiso has developed a remote type E Monitor–-the first step of complete E Monitor systemization. The remote device uses output signals from the field type E Monitor to view the same commands as the field type E Monitor but at a central control room. The remote type monitor now determines bearing wear without the need for on-site inspection. It also has a contact function (warning) just in case pre-set values are exceeded, so that the pump can be stopped by triggering a protective circuit when a bearing has abnormal wear.

3.Data collection and monitoring system

As one remote type E Monitor is needed to pair with the corresponding field type E Monitor, it is useful when monitoring only a few units or for stand-alone pumps. For managing multiple pumps however, the system takes up considerable space and is less convenient. There are two additional requirements: new monitoring methods are required to keep down the initial investment (eliminating wire embedding costs and DCS); maintenance data are required to collect simultaneously with periodic inspection To meet these needs, Nikkiso has developed a data collection and monitoring system (called the data collecting E Monitor) as the second step of monitor systemization.
The data collecting E Monitor analyzes highly accurate data (e.g., operation time, wear state) to achieve even more reliable preventive maintenance (Figure 2).

1. Using infrared communications, an explosion-proof data collection system gathers data during routine inspections.
2. Data are stored in a PC.
3. Trend graphs for pumps are displayed and the need to replace bearings is predicted.

Figure 2: Data Collection and Monitoring System Flow

Summary

To reduce costs, the demand for saving energy and reducing labor is growing rapidly at production plants, etc. Due to easy, accurate trend monitoring of pump bearing wear, maintenance staff—using the E Monitor series—can accurately predict when maintenance will be needed. In addition, companies can now choose the best monitoring method based on their environment, which can reduce total production costs.