Most centrifuges have an Emergency Stop button, also known as the E-Stop button. While the E-Stop has a safety purpose, it’s not the preferred way to shut down the decanter centrifuge. An E-Stop is only to be used in emergency situations.
So, what qualifies as an emergency situation?
An emergency situation is any situation that poses an immediate threat to a person's health, security, property or environment. There are four event types that qualify as an emergency:
- Catastrophic Mechanical Failure. This is a sudden and total machine failure that forces you, the operator, to leave the centrifuge area immediately. The centrifuge can’t be shut down normally (using the control panel and accessing the centrifuge shutdown screen, because this takes more time than pressing the E-Stop button).
- Water, Oil or Feed Line Leaks or Ruptures. If a line breaks and there is water, oil or feed pouring out, it’s quicker and safer to use the E-Stop rather than a normal shutdown so you can contain the situation as fast as possible.
- Fire. The centrifuge or the centrifuge area is in flames, smoke or both.
- Safety. To prevent electrocution or injury to an anyone touching or near the centrifuge.
DO NOT use the E-Stop button in these instances:
- Normal Centrifuge Shut-Down. If you are not in an emergency situation, always perform a normal centrifuge shut-down from the control panel.
- Convenience. Do not be the lazy person that uses the E-Stop button just because you don’t want to wait for the centrifuge to shutdown normally (via the control panel). You can cause unnecessary damage to the centrifuge. The E-Stop button doesn’t mean the centrifuge shutdown time is shorter. In most cases, a normal centrifuge shutdown actually stops the centrifuge faster than an E-Stop. A normal shutdown controls how long a rotating centrifuge comes to a complete stop. With an E-Stop, since power is cut off immediately, a rotating centrifuge coasts to a stop. The centrifuge continues to spin due to momentum and gradually slows down, this can take up to an hour.
- Non-Emergency Alarm. If a non-emergency alarm appears on the control panel and you cannot access the shut-down screen page, do not use the E-Stop button. Instead, you should push the button to silence the alarm. But don’t reset the alarm. Resetting the alarm without resolving the issue will trip the alarm again. The cause for the primary alarm needs to be resolved. You should contact Centrisys for centrifuge service.
What does the E-Stop button do?
- It stops lubrication to the centrifuge and stops the hydraulic backdrive pump unit. This leaves the centrifuge full of solids, causing unbalance on start-up. This could trip the vibration alarm, which will shut down the centrifuge.
- Don’t touch any wires. The power to all motors and control devices are turned off with an E-Stop. However, some motor wires may still carry a voltage as the motor still generates electricity as it coasts to a stop.
To use the E-Stop button in an actual emergency, it's as simple as:
- Pressing the E-Stop button.
- Rotating the E-Stop button clockwise or pulling out the button to release (styles may vary on Centrisys centrifuges).
How do you reset the E-Stop button?
- As soon as your emergency situation is over and it’s safe, you need to perform these steps in this order even if your centrifuge has not come to a complete stop. Keep in mind that a centrifuge can’t start-up with an active E-Stop alarm.
- First, make sure the main power source and/or main disconnect is still powering to the centrifuge. The main power source is located at your company’s main breaker. The main disconnect is located at the right side of the panel.
- Next, you need to reset the E-Stop button. Pull or rotate the E-Stop button clockwise allowing it to pop/release the button, then press the yellow reset button near the E-Stop to engage the master control relay (MCR) inside the panel. This turns control power back on for the auxiliary equipment.
- Now check the main screen and clear any flashing banner alarms.
- The last step is critical. Immediately turn on the hydraulic backdrive pump unit, the lubrication system (only if your centrifuge has air/oil or recirculated lubrication) and the bowl flush. This will clean residual solids out of the centrifuge. If you don’t turn on your hydraulic unit or the lubrication system, a spinning rotating assembly with a stopped hydraulic unit and lubrication system will turn off lubrication to the bearings and Rotodiff. This can cause accelerated wear and possible permanent damage to the bearings and Rotodiff.
- Centrisys highly recommends to perform a clean in place (CIP) to have the centrifuge further clean out the solids and help with balance. The CIP will also shut down the centrifuge properly and it’s at this time you can properly restart the centrifuge safely.