Using a Urinometer

Summary

The video script explains the process of calibrating a urinometer using distilled water and measuring the specific gravity of urine samples. It emphasizes the importance of careful handling to prevent errors, such as avoiding wetting the urinometer stem or letting the float stick to the vial. Calibration adjustments are needed if water temperature deviates from 20ºC, with examples of adding or subtracting correction factors. After calibration, urine samples are tested, and proper cleaning of the equipment is highlighted once testing is completed.

Takeaways

• 💧 The urinometer must be calibrated in distilled water before measuring the specific gravity of urine.
• 🌡️ The specific gravity of distilled water is 1, and the urinometer should read this when calibrated correctly.
• ⚖️ To calibrate, fill the urinometer vial 2/3 full with room temperature distilled water and carefully lower the float into it.
• 🌀 A slight spin should be imparted to the float to prevent it from sticking to the vial walls.
• 👁️‍🗨️ The reading should be taken at the bottom of the meniscus, and your eye must be level with the meniscus for accuracy.
• 🌡️ If the urinometer does not read 1, a temperature adjustment may be needed, especially if the room temperature differs from 20ºC.
• ➕ If the water temperature is above 20ºC, a correction factor (e.g., +0.005) should be added to the urinometer reading.
• ➖ If the water temperature is below 20ºC, a correction factor (e.g., -0.002) should be subtracted from the reading.
• 💧 After calibration, the urine sample is measured by following the same procedure used for distilled water.
• 🧼 Clean the urinometer and vial with soap and water after testing all samples to ensure accuracy and cleanliness.

Q & A

What is the first step in calibrating a urinometer?

The first step is to fill the urinometer vial 2/3 full with room temperature distilled water.

Why should you not drop the float into the vial?

The float has a weighted end, and dropping it into the vial may cause it to break.

How can you ensure that the float is not stuck to the side of the vial?

You should impart a slight spin to the float to make sure it is floating in the middle of the vial and not stuck to the wall.

Why is it important to avoid wetting the stem of the urinometer?

Wetting the stem can throw off the specific gravity reading.

At what point should you read the specific gravity measurement on the urinometer?

You should read the measurement at the bottom of the meniscus when the float stabilizes, and make sure your eye is level with the meniscus.

What is the standard specific gravity of distilled water for calibration purposes?

The specific gravity of distilled water is 1.

What should you do if the specific gravity of distilled water is not 1?

You should record the temperature of the water and apply the necessary correction factor depending on whether the temperature is above or below 20ºC.

How do you adjust the urinometer reading if the water temperature is above 20ºC?

A correction factor must be added to the urinometer reading if the water temperature is above 20ºC.

What was the correction factor applied when the water temperature was 35ºC?

The correction factor was .005, which needed to be added to the urinometer reading.

How should you clean the equipment after measuring urine samples?

After testing, rinse the vial thoroughly with water between samples, and clean the urinometer float and vial with soap and water when finished testing all samples.