Quantitative Tests and PM tips for Autotransfusion Units

In today’s blog we are going to take a break down quantitative tests for autotransfusion units. In addition to the quantitative tests, we will share a few preventative maintenance tips for the system as well.

Before you begin any tests, quantitative or qualitative, it is important that you look at the specific directions from the original equipment manufacturer. Often times, the OEM has specific instructions that vary amongst different systems.

In order to perform the quantitative tests, you will need the following test apparatus and supplies:

• Leakage current meter or electrical safety analyzer
• Ground resistance ohmmeter
• Leak-detect solution
• 1,000 mL graduated cylinder
• Stopwatch or watch with a second hand
• Bucket with capacity of at least 1 L
• Set of disposables for autotransfusion unit
• Stroboscopic tachometer

Quantitative tests

1. Grounding Resistance: Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 ?. If the system is modular or composed of separate components, verify grounding of the mainframe and each module or component. If the device is double insulated, grounding resistance need not be measured; indicate “DI” instead of the ground resistance value. If the device has an accessory receptacle, check its grounding to the main power cord.
2. Leakage Current: Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. Measure chassis leakage current with all accessories normally powered from the same line cord connected and turned on and off. This includes other equipment that is plugged into the primary device’s accessory receptacles, as well as equipment plugged into a multiple-strip outlet, so that all are grounded through a single line or extension cord. Chassis leakage current to ground should not exceed 300 µA.
3. Roller Pumps: Check the rollers on pumps to make sure that they are running smoothly and that there are no unusual noises from bearings or other indications of excessive bearing wear. Using tubing of the correct size and hardness in the pump, immerse both ends of the tubing in a bucket of saline solution or water at atmospheric pressure and turn on the pump. (This may require triggering of some sensors for the more automated units; contact the manufacturer if it is not clear how to get the pump to run.) To check pump accuracy, set it to deliver 500 and 1,000 mL/min, and collect the volume for a convenient time interval in a calibrated 1,000 mL graduated cylinder. Flows should be accurate to within 5% of the setting or the manufacturer’s specifications.
4. Vacuum Pump: Check the accuracy of vacuum pump regulation on units equipped with vacuum pumps by connecting a length of tubing to the vacuum port and to a vacuum gauge. Vacuum levels should be within 50 mm Hg of the displayed value at full vacuum.
5. Centrifuge Speed: Measure centrifuge speed with a stroboscope tachometer illuminating the centrifuge bowl chuck while the centrifuge is spinning. A piece of tape may be applied to the chuck to facilitate speed determination. Centrifuge speed should be within 10% of the specified speed or within the range specified by the manufacturer. If centrifuge speed is outside of acceptable specification, contact the manufacturer to inquire about adjustment.

Preventive maintenance

• Clean exterior and clamps, as needed.
• Lubricate per manufacturer’s instructions.
• Replace motor brushes, drive belts, and centrifuge bowl O-rings, as appropriate.