Flow Control Orifices

Posted on July 24, 2018

Flow Test Correlation of Size and Flow

Customer Challenge to Accu-Glass:

A customer needs a flow restrictor but only knows what liquid flow rate is needed and what pressure they will be using. Accu-Glass will develop custom Microbore glass flow restrictors with an inside diameter (ID) determined to meet the customer fluid flow requirements.


Glass Microbore Tubing provides precise and constant flow rate delivery, which make ideal flow restrictors. Air flow testing is a quick and accurate way to measure the ID verses a liquid test. Accu-Glass is capable of delivering tight precision (+/-0.001”) for the glass ID using a low cost short run conventional glass drawing process.


Using the customer provided liquid flow rate and pressure, a standard product length is agreed upon. With these specifications, Accu-Glass will calculate the theoretical ID that is needed to obtain the desired liquid flow. Using this ID and length, a target nominal air flow value is calculated in SCCM’s.

The ID is measured to this nominal flow using the Pressure Decay flow testing method during the glass drawing process.  All of the parts are then cut and sent through our automated flow testing equipment where the final finished product is 100% verified to ensure compliance with the customer’s fluid flow specification.

After the 100% flow-test, the parts are packaged and shipped to the customer for verification against their liquid flow test. After the customer performs their liquid test, we can then determine if we need to make any adjustments to the ID and nominal flow. Most times this can be done on the first run, but can take two or three runs to get the proper correlation between liquid flow and air flow.


At  Accu-Glass we are ready help you with all of your glass flow control orifice needs.  Our Engineers are ready to help you with the design process, prototyping and scale up to high volume production phases of your product development.