“Ball In The Wall” Not Effective For COVID-19 Control

Controlling COVID-19: Hospitals

Very basic and antiquated devices such as the “Ball In The Wall” negative room pressure monitors are highly ineffective in preventing cross-contamination from infectious disease such as COVID-19 (Coronavirus).

Hospitals have a monumental challenge ahead in light of the world-wide outbreak of the contagious COVID-19, otherwise known as “Coronavirus.” Now more than ever, hospitals are designing and preparing controlled environments with specialized air filtration systems (HVAC) and instrumentation to monitor differential room air pressure to reduce the possibility of cross-contamination from patients who test positive for COVID-19, or may show early symptoms of this deadly flu virus.

As with any infectious disease, hospitals typically quarantine patients in negative air pressure isolation rooms, or simply “negative pressure rooms.” This means air outside the patient’s room is maintained at a higher pressure than the air inside the patient’s room. Basically, when the patient’s door is opened by hospital staff the air will “rush” into the room, thereby preventing infected air from inside the patient’s room from escaping into the hall or adjacent room. CONTROLLING THE SPREAD OF THIS DISEASE IS VERY DEPENDENT ON THIS PROCESS WORKING AS IT SHOULD.

The anatomy of a negative pressure isolation room can be very basic, or very complex. All negative pressure rooms, however, require instrumentation to monitor negative room pressure. The go-to for many decades has been the “Ball In The Wall” which basically is a plastic tube which contains a Styrofoam ball inside. It has a small vent on either end, and passes through a wall between the controlled space (negative pressure area) and the positive pressure area.  Depending on the pressure levels, the ball will move forward or backward as pressure levels increase or decrease. About 60 years ago, this was a sufficient solution, because it was the ONLY solution.

These “ball-in-the-wall” devices are not only very inaccurate, but do not provide ample notification when and if a controlled environment becomes compromised. In essence, this means if a negative pressure room becomes compromised because of an air lock leak, HVAC issue, electrical problem, etc – then every single patient, and all staff in the hospital are at risk of contamination.

Alternatives Are Mandatory

Technology is accelerating at an incredible rate. No one knows this better than the healthcare industry; they usually take full advantage of technological advancements in order to provide more comprehensive patient care and safety. But using the ball in the wall is an exception to this rule. Some hospitals and treatment centers are still relying on age-old devices like the ball in the wall to prevent the spread of infectious disease. A tube containing a Styrofoam ball is in no way precise enough to provide protection against the spread of disease; especially if on one side of that wall there is a patient with a communicable disease or virus like COVID-19.

One such alternative would be to integrate stand-alone digital differential room pressure monitoring instruments. Ideally, these devices would be able to immediately and simultaneously alert staff, facilities managers and caregivers if conditions inside an isolation room become critical. Local alarms (in-the-room high decibel alarms), immediate automated emails sent to staff, and SMS messages sent to caregivers would help to provide immediate quarantine protocols. With ball in the wall type devices, if no one is looking directly at it – they have no way of knowing if there is an issue. In the case of potential contamination, every millisecond counts.

As technology advances, costs decrease. What may have once been a barrier for adoption due to cost, are is now no longer an issue. In fact, there are many products on the market which provide a high level of advanced warning and monitoring for patient isolation rooms, and are very similar cost as ball-in-the-wall type products.


The CDC is warning all healthcare facilities to immediately revise protective policies and procedures to prepare for what is expected to become a wide-scale pandemic. A great start for healthcare providers on the road to ensuring public safety would be to take inventory of any and all controlled environments, isolation rooms, cleanrooms, etc and take note of which of those controlled spaces are relying on ball in the wall type of room pressure indicators.

We at Two Dimensional Instruments have created a comparison showing features of a completely digital-based early warning monitoring system for room pressure as compared to a ball in the wall type of monitor. In this comparison, a “TV2 Cleanroom Monitor (TV-202)” was compared to the “Ball-In-The-Wall” brand of ball-type room pressure indicators/monitors.

All other features aside, perhaps the most important point of differentiation between the TV2 and the Ball In The Wall is the ability to not only receive advanced email/SMS alerts when conditions are unfavorable, but also the ability to log, chart and store all data points. This means you’ll never have to guess what the status of the room is/was at a given point in time. The TV2 Room pressure indicator can store over 80,000 data points (about 2 years worth if logging every 10 minutes) and can be exported in excel format.

Call us today to see why the TV2 Room pressure Monitor is the best pressure indicator for your hospital.

Call now: 877-241-0042