The dynamic distribution of validation studies: open the door and defrost cycles

We received a lot about the dynamic distribution of customer validation studies and monitoring applications.These problems usually lead to delve into application details, using method and the basic principles of interesting communication.In this blog, we will share visa senior GxP regulatory professionalsPaul, Daniel,A communication with a customer, the customer is an installation/operation/performance verification service providers, responsible for freezer, verification and validation studies performed periodically dynamic distribution.

Dear Paul:

I'm reading blogs"During validation using MKT to prove the rationality of the normal temperature deviation: you should do so?"Think of several questions.I am curious about the freezer defrosting cycle, I want to know is, with built-in defrosting cycle and make temperature deviates from the acceptable range of cooler and freezer, recommend you with what method.

I have three questions:

We have largely depends on the product to accomplish most of the work visa, you seem to be very proficient in these themes, so I want to hear your opinion.

Thank you very much!

- C

Hello, C:

About multiple air sensor and a buffer probe to the first question, it sounds like a kind of new method.According to my experience in dynamic distribution validation studies, I used the air probe or buffer probe, but never mix.For me, your method sounds reasonable, but if I used this approach, I will be in the buffer probe placed directly next to an air probe, in order to comparing with all other air probe.

I assume that you want to use the buffer the cause of the sensor for dynamic distribution of validation is to prove that monitoring probe (may) in ethylene glycol buffer can accurately represent the freezer.But maybe your motive is to prove that the location of the bad situation is not actually that bad.I think it depends on the location you put buffer probe.For me, the question boils down to: what are you going to how to deal with data from a single buffer dynamic distribution test location?The answer to this question can solve the probe should be placed in where.That is why I tend to use all buffer probe, or all use air probe;I want to use the data to prove freezer were well performance in any store scenario, or due to buffer temperature fluctuations needs certain space to store the necessary restrictions on the object.

For is to buffer probe placed in the center or in case of bad position to the second question, we have multiple blogs about these topics (link below).

Dynamic distribution, the temperature cooler validation will be sent to what degree
•Cold/hot: fridge monitoring actual need how many probes?
•Temperature probe of damping phenomenon: location, time and reason

But for this discussion, I will briefly in my opinion, I think the position is determined by the way we analyze the data.

The maximum and the minimum is important compared with rapid acceptance criteria.I have never seen a company will monitor sensors placed in the "hot spots" determined by the dynamic distribution of validation studies.At least in the treatment of the detached or not when the freezer, cooler because they usually have small internally and will not run out of storage space for using sensors.Small freezer in monitoring sensors are usually installed in the chamber wall opposite the door hinge finally.Therefore, I would anticipate that, then the buffer probe placed in any position you intend to place detector (next to put an air probe).

Finally, you asked to open cycle compared with defrosting cycle problem.Although this is an interesting way, but I remind you don't do it, because we cannot know to open the door and defrosting state on the temperature or the duration is comparable.

Let's discuss this issue more deeply.Open the door only from the front to the hot air into the freezer.Usually involves heating defrosting cycle, by contrast, spiral pipe, warm air into the short time (usually) from behind.Open the door from the front to the warm air, and defrost cycles from the back of the freezer conduction of heat.I think between the two is not directly comparable.

I suggest you next time for dynamic distributed authentication, a preliminary study to determine the frequency of defrosting.After know this information, you should be able to in the process of dynamic distribution of validation to capture a defrost cycle, see how bad it is.

Thank you, Paul!Here are our dynamic distribution of validation studies some background: in the process of our air refrigeration indoor temperature for the 24 hours of the dynamic distribution of validation.This usually can be captured during one to three defrost cycle.We repeat the study in load conditions and similar results are obtained.Then we studied the open the door, open the door a minute to simulate the typical usage of equipment.

Our idea is, from the door in the study collected data can be easily directly comparing with defrosting cycle.We will be able to analyze the data, and view the defrost cycle duration and effects are actually in all validation position dynamic distribution is more significant than the effect of open research or less significant.

Typical defrosting cycle, for example, the highest temperature is 10 ° C, it will have three minutes of temperature deviation.Open cycle may to 15 ° C, the highest temperature deviation from the temperature of the duration for five minutes.Of course, if the defrosting effect is more significant, we will need to consider other ways to prove the rationality of using freezer (for example, the way described above using ethylene glycol probe).

I completely agree with different heat source, but if the influence of defrosting is less than the impact of open the door, can't we claim that the influence of defrosting is less than the influence of the typical open usage?

Please keep in mind that we are a IOPQ service service company.We don't have the freezer/cooler.Therefore, strictly speaking, while discussing the probe location, I mentioned are dynamically distributed authentication probes, rather than equipment owners to track temperature monitoring equipment.

- C

Well, I think I understand your theory basis.If typical defrosting cycle, the overall impact of less than the influence of typical open the door, so we can defrost cycle is regarded as "normal use", because we will open the door as "normal use".I agree this is more likely to be very interesting, but I fear it may be the cause of such a situation, which you have data show that defrosting cycle and the impact of the door is not acceptable, need to reduce the influence of both.Another theory is that too loose open policy may cover up the negative impact of defrosting period.(although you look very normal defrosting cycle.)

Please keep in mind that in ethylene glycol buffer probe can not alleviate the problem, but will be hidden.Practical measures of reducing the risk of product including program control (for example, is not stored in the freezer small volume items) or limit to open the door of time or frequency.

I hope these information are helpful to you!

Another, please refer to our recent revision of the application instructions:"To study the dynamic distribution of validation/put sensors in the application of five rules"

You is there any further ideas or questions about this topic?In the field below, please express your opinion.