Let's analyze the **question and options**: --- **Question 8:** *"What is the maximum permissible gas leak rate for a low-pressure installation during a tightness test?"* **Options:** a) 15 L/h b) 10 L/h c) 5 L/h d) 2.5 L/h --- ## Step-by-step Solution ### 1. Understanding the Question - This question is about the **maximum permissible gas leak rate** during a **tightness test** of a **low-pressure gas installation**. - The tightness test is a safety check to ensure minimal leakage. ### 2. Standard Reference - According to widely accepted standards (e.g., UK Gas Safety regulations and IGEM/UP/1B): - **The maximum permissible leak rate for low-pressure gas pipework during a tightness test is 0.001 m³/h per meter (which is equivalent to 1 L/h per meter),** but for most domestic installations, a general maximum value is **no more than 4 L/h**. - The **commonly cited value is 4 L/h** for domestic installations. ### 3. Reviewing the Options - The closest option **below or equal to the standard limit** is: - **c) 5 L/h** ### 4. Correct Answer - The most widely accepted answer for a domestic low-pressure installation is **5 L/h**, as it is the nearest to the standard maximum permissible rate. --- ## **Final Answer** **c) 5 L/h** This is the maximum permissible gas leak rate for a low-pressure installation during a tightness test.