Hydrostatic Pressure or Pneumatic Pressure Test – Which One Do I Need?

The plumbing industry is loaded with industry jargon that plumbers need to learn and their necessary piping skills. Some of these terms certainly put colorful ideas in our heads. Honestly, how are we supposed to react when our plumbing technician tells us we need a new hose bib, we have a leaky nipple, or heaven forbid…we have busted our ballcock.

Yeah, the plumbing business is a regular riot.

It is important to know if your plumbing is leaking, as water damage is responsible for the most costly claims against homeowners’ insurance policies. Of equal –if not greater—importance is discovering leaky gas lines before they have an opportunity to fill your house with poisonous fumes –or worse—spark an explosion. Two different types of pressure tests are available to plumbing technicians, one specific to drain lines and one for gas lines; let’s take a look at which tests may be suitable for you and your potential leak.

What is a Hydrostatic Pressure Test? 

When broken down into its Greek origin, the term hydrostatic means balanced water. Hydrostatic pressure testing is used to determine the existence of leaks in a home’s plumbing drainage system. The method is also commonly used to determine the structural integrity of fire extinguishers, water heater tanks, and oil tanks.

In residential plumbing, hydrostatic pressure testing takes place across several simple steps:

  1. Removal of a toilet from a ground-floor bathroom.
  2. Install an inflatable ball into an outdoor sewer cleanout access port.
  3. Inflate the ball to block any water from escaping through the drainpipe. 
  4. The plumbing technician will observe the water level in the toilet drainpipe for 15 – 30 minutes to see if the water level drops. 
  5. If the level doesn’t drop, your drainage pipes are free of leaks, and the technician will replace the toilet and remove the inflatable ball.
  6. If the water level does drop, there is an active leak somewhere in your drainage system, which requires further investigation.

Hydrostatic testing is an excellent method for determining the existence of a leak, and once a leak is discovered, your plumber will begin isolation testing. Isolation testing uses the same process, except that the tests are performed on smaller sections of the piping system to locate the leak’s source accurately.

When Should I Get a Hydrostatic Test?

Most of our plumbing pipes, fittings, and fixtures are hidden behind walls, in cabinets under sinks, and buried beneath our concrete slab foundations, making it difficult to see which pipe is the culprit. Most often, the homeowner’s first indication of a potential drainpipe problem is things like slow drains, gurgling sounds, and horrific smells.

Other indications that there could be a leak in your drainage pipes include damp spots in carpeting or drywall, cracks in walls or concrete foundations, and standing water near the foundation. Not only can drainpipe leaks cause thousands of dollars in damage to your home, but raw sewage leaks can wreak havoc on your family’s health as well.

What if I Fail My Hydrostatic Test?

If the overall hydrostatic testing indicates a leak, the plumbing technician will begin isolation testing individual pipe sections. Again, with most of our plumbing hidden from sight, pinpointing the exact location of a drainpipe leak is nearly impossible without removing some portion of flooring or drywall. When the source of your drain leak is identified, you and your plumbing technician can discuss repair or replacement options and potential costs. 

What is Pneumatic Pressure Testing? 

Residential pneumatic pressure testing refers to a procedure where air or nitrogen is introduced to a sealed storage or delivery vessel, such as an oil tank or a gas line. 

Nick’s Plumbing uses pneumatic pressure testing to check the integrity of your home’s natural gas lines in these steps: 

  1. We start with visually inspecting all exposed sections of gas piping, with particular attention paid to fittings and connections that may have signs of wear or leaks. 
  2. Close all gas supply valves that are located throughout the home. Turn off gas service to the entire house at the meter. 
  3. Inform your plumbing technician about what gas-powered appliances you have, including water heaters, furnaces, stoves, hot tubs, outdoor kitchens, clothes dryers, or generators. 
  4. Connect a specialized air compressor to the gas line on the house side of the meter and pressurize the line. The amount of pressure used in the test should slightly exceed the normal force the line is under in normal use, and the line must maintain that pressure for the duration of the test, usually fifteen or thirty minutes.
  5. Once the line is pressurized for the test, the tech can start to check for leaks at various connections and fittings, spraying them with a mixture of dish soap and water. If any bubbles appear in the solution sprayed on the fitting, there is a gas leak. 
  6. If the gas line can maintain the amount of pressure for the length of the test, there are no leaks present.
  7. If the line allows for the internal pressure to decrease during the test, there’s a leak somewhere in the gas line. 

When Should I Get a Pneumatic Pressure Test?

A pneumatic pressure test is most effective for residential customers at locating leaks in gas lines located outside the home. An indoor gas leak is usually easy to detect, thanks to the chemical additive mercaptan that gives natural gas that “rotten egg” smell it’s famous for. Leaks in the outdoor gas lines or those in attics and under pier-and-beam foundations can be challenging to locate due to wind activity and often go for weeks or months without detection.

Some possible signs that you could have an outdoor gas leak could include unusually high monthly gas bills, dead or dying plants, hissing noises, along with an “orange-y” color to any gas flame in the home. 

What if I Fail My Pneumatic Pressure Test?

If the pneumatic test indicates a loss of pressure, it can be assumed that there is a leak somewhere along the gas supply line. If a leak is discovered during a pneumatic test, it needs to be repaired or replaced before restoring gas service. 

Nick’s Plumbing & Air Conditioning has been performing hydrostatic and pneumatic tests across the Houston area for over forty years. Based in the Historic Heights district since 1979, Nick’s has earned a tremendous online and “word-of-mouth” reputation for our expertise, our service, and most importantly, for our employees. 

If you’re experiencing symptoms of either a gas line or plumbing drainpipe issue, give Nick’s Plumbing a call today.

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