Below we have answered some of the most common questions we receive regarding our product. If you cannot find an answer to your question below please contact us and we will be happy to assist with your enquiry.
The priming is done in two ways, depending on the product. The single flow is either incorporated in the set within 100 mm of the luer lock and therefore primes very quickly up to the flow controller, thereafter primes the last 100mm at the set flow rate. That is usually fairly quick given the short distance. The other single flow, which is a luer lock itself attaches to the venous access catheter, the IV set (any set can be used) is primed and attached as normal. Or the flow controller is attached to the luer lock of the IV set and then primed. The MultiFlow we designed has 6 flow rates, Off position and Open or prime position
The head of pressure is from the bag or bottle height to the outlet. What is in between doesn’t matter. Therefore, the controller can be anywhere along the IV tube. This is easy to prove, Just set the flow rate with a roller clamp and as long as you don’t move the outlet or the bag hook, you can move the roller clamp up and down and no change to the flow rate will happen.
The single flow can not change flow rates. The luer lock single flow would be kept like needles. Various sizes and colours. When a change is needed, the flow controller would be changed. These are not meant to be used where frequent changes are expected (ICU etc). They are best suited for drug delivery (eg: antibiotics) where changes are not expected. The IV set would be any set that the hospital prefers to use and would need a roller clamp or a slide clamp to use as an ON/OFF switch. The MultiFlow, as explained above can be closed and opened and has 6 flow rates in our current configuration. More or less flow rates can be configured as required.
The Acu Rate flow controller is designed in such a way as to remove friction from the system. The length of the flow controlling tube is near zero, therefore, the friction is also near zero. What this means practically, is that the flow through the controller is turbulent and therefore follows Bernoulli’s equation. This equation does not have viscosity as a variable. Therefore, a variety of viscosities from saline to 50% to dextrose can be infused with no change in flow rate.
The flow controller is in fact not independent of pressure, but it does depend on the square root of pressure as per Bernoulli’s equation. In practice this means as the pressure changes, the flow rate only changes with the square root of the pressure change rather than being directly proportional to the pressure change as all other controllers are. Therefore, elastomeric pumps and other devices where the pressure varies become more accurate.
Yes. Both single and multi flow controllers have been tested under pressure with elastomeric devices. The single flow controllers have been tested and work up to 500 kPa of pressure.
No. Your system accuracy depends not only on the flow controller but the rest of the system and in particular the pressure source. The flow controller itself is accurate to ±3% and if the pressure is constant, then your system would indeed be accurate to ±3%. This is never the case; therefore, the system is dependent largely on these two factors.
There is no fixed maximum rate. Virtually any large flow rate can be achieved. The minimum flow rates depend very much on the pressure of the device. At 500 kPa, the minimum flow rate achieved so far is around 4 mL per hour. Flow rates down to 0.5 mL per hour can be achieved but the cost may also be higher.
In many ways the two devices are quite different. All devices similar and including Dial-a-Flow work on the principle of friction. They rely on varying the length of the controlling tube to control the flow rate. Although they have an indication of flow rate written on the side, the numbers are not accurate and do not really mean anything. The flow rate is completely dependent upon the pressure, viscosity and ambient temperature. To set up a Dial-a-Flow device is similar to setting up a roller clamp. Hence the accuracy or lack of is also similar to a roller clamp. Depending on the device, there is also some evidence that the flow rate does indeed change over time due to the device itself. The only advantage of a Dial-a-Flow type device is that it is safe from runaways.
The Acu Rate MultiFlow device has all the features of the single flow device with the added benefit of being able to change flow rates. Otherwise, the device itself is accurate to ±3% for each different flow rate.