Which system is better R 404A or R 717?

[smpsmp45]

I know this question might have been discussed earlier many at times. Lots of Theoretical issues are put forward to counter each & the other.

I am looking at practical aspects of each system. We work with R 404A as well as Ammonia & would like the clients to go in for R 404A systems. But in Comparisions, we may be missing something & hence this issue is again put up on this forum.

So Pros & cons pl including economical aspects & more importantly practical aspects

[US Iceman]

If you do not mind, let me switch the question around.

Why are you recommending R-404a?

[smpsmp45]

Let me be very specific as to what points we put up with our clients & I shall pu up all those.

[Samarjit Sen]

If the choice is between R 404A and 717, I would prefer to use 717.

Of course presuming it is a low temperature application.

[US Iceman]

Samarjit,

Why just low temperature applications for ammonia?

[Samarjit Sen]

Mike,

In our country I am yet to see ammonia being used for air conditioning. As you know I am very new to ammonia, although long time back I had done some Cold Storages with ammonia, but the experience had not been much.

[TXiceman]

Seen several ammonia water chillers designed around semi-welded plate and frame chiller and condenser. A very compact design and a low charge. Something on the order of 1# of NH3 per ton of capacity.

One industrial customer has been replacing all of his old r-11 and R-12 chillers with screw/ammonia chillers for several years now.

A few years ago I put in two 2000 ton ammonia water chillers.

As I have said...best to stay away from the 400 series refrigerant for any thing except the smaller systems. The customer needs to look at R-134a for high temp and as we go lower, R-507.

Ken

[US Iceman]

In our country I am yet to see ammonia being used for Air conditioning.

This is something you have to be careful with, but it does work very well. I would not recommend a direct ammonia system for AC purposes. Any ammonia that might escape woul dcreate a huge panic among the office occupants.

On the other, if you do as TXiceman suggested and use ammonia to cool water or glcyol in an indirect system, the ammonia is separated from the occupants of the building.

All of this is dependent on your local building codes and refrigeration codes.

Ammonia low temp and ammonia high temp are the same thing, except the operating temperatures of course.

[Samarjit Sen]

How does the cost compare with using ammonina as an indirect system of cooling with ***** for a similar project.

[US Iceman]

Well, with a direct refrigeration system the refrigerant is pipe directly to the evaporators. This means relatively smaller pipe and just about anyone can install copper pipe with some guidance.

With an indirect system, the refrigerant indirectly cools the space to provide AC. Here the refrigerant cools let's say water (in a chiller). Then the water is pumped to the cooling coils to provide the AC. This type of system requires relatively larger pipe, plus the pumps and the associated pumping power.

The piping systems difference in cost, plus the pumping power contribute to the overall cost impact.

On the other hand, ammonia is very cheap compared to those other refrigerants.

It's not only a cost consideration but also one of occupant safety and the required codes.

[Samarjit Sen]

In our ****ry, use of refrigerant Ammonia is not allowed within the City limits, and as such its application for Air Conditioning is not possible. It is generally used for Cold Storage application and other industrial applications out side the City limits.

What I have noticed that in ammonia the main problem is leakage of refrigerant. These leakages occur from the shaft seal of the open type compressors and scondly from the various valves inthe system, which are mostly non standard.

Are their any semi hermetic compressors available so as to ensure the non leakage from the shaft seal, and valves and fittings of standard make who can ensure the sealing.

[brian_chapin]

What I have noticed that in ammonia the main problem is leakage of refrigerant. These leakages occur from the shaft seal of the open type compressors and scondly from the various valves inthe system, which are mostly non standard.

Your results may vary but from my experience:

99.9% of ammonia leaks are via operator error (assuming we include lack of preventative maintenance as an operator error)

I have never had a significant shaft seal leak - we change them out when they drip more than 5 drops of oil per minute. I imagine that if you let them wear until failure that you could have one hell of a mess.

Ammonia valves in the US are very standardized and extremely rugged. Many of the main manufacturers valves are actually flange-to-flange compatible. As for valve leakage, it isn't really a concern if you routinely (yearly) anti-sieze and excercise the valves. Many ammonia valves (especially the larger ones) can be backseated and repacked while the system is charged without leaking refrigerant.

I can't post URLs for you but we look for Hansen and Parker R/S for our NH3 valve needs. We've recently started experimenting with some Danfoss sealed motor valves as well with great success.

For what it's worth, I don't think that ammonia leaks more often than the other refrigerants at all. In fact I know in our case that it is quite the opposite. The difference is that if you leak 1lb a day of ammonia from a valve in your engine room you will almost certainly KNOW about it where in a R22 system you will likely have no clue.

Our experience with a 14,000# ammonia system and a 20,000# R22 system (run by the same company) is this:

We've put about 2000# a YEAR into the R22 system. We've put 2500# total into the ammonia system over the past 10 years including the addition of 2 liquid recirc evaps.

[TXiceman]

The big advantage of the indirect system is all of your refrigerant piping and charge is confined to one small area, where on a direct system, you have refrigerant piping run to al of the users. The long runs of refrigerant piping now have to be tight and run per the required codes and are more of a problem when leaks develop. Water piping is fairly easy to run and repair. A water leak is much cheaper than a refrigerant leak.

As for temperature penalties, on the indirect system, the use of welded plate exchangers will minimize this issue.

Ken

[Samarjit Sen]

Hi Brian Chapin,

You are quite right and I do accept the fact. The problem here is that most or rather all the Ammonia Plants are basically for Potato Cold Storages or some thing like it. The user in order to save money catches hold of a technician who may have no knowledge of refrigeration and may had worked with some one in an ammonia plant. He becomes the authority and gives the consultancy as well as install the plant. He gets local make compressor and equipments from those people who are willing to pay him a commission. He installs he plant. The user feels that keeping a man for operation would be expensive , so he prefers to keep some one who has no experience in this field. The result is that after a couple of years the complete plant breaks down.

I have visited a large number of plants of ammonia and on seeing the plant ( or rather the contraption ) was surprised that hoe did it operate. When I tell the user that he has to scrap the plant and install a new one which besides giving him an efficient performance will also reduce his power consumption. The reply is the same, " will let you know ". The matter ends there and in comes the so called authority and starts all over again.

So what I had said was sheer out of seeing the situation here. I would love to install a sample plant of ammonia, provided one is willing to pay. Am trying to locate one.

[Samarjit Sen]

Hi Ken,

I am waiting to get an oppurtunity to install an ammonia plant, and will surely seek the guidance from all of you. At present my mind is on CO2. I am trying to convince a customer for installing a CO2 plant with a cascade system with ammonia for his hardening Chamber and Cold Storage of Ice Cream.

[TXiceman]

Sen, Co2/NH3 plants are a real and up and coming approach to lower temp refrigeration. The lower limit is set by the triple point of the CO2, however, there has been some work done at lower temperatures and the use of a "slurry" in the evaporator. I believe there is a plant operating in Europe with this design.

I had proposed CO2/Ammonia cascade a few yearsback before much work was done in this are and the customer was swayed by a competitor that had lots of sales experience, but little technical experience. He operated on the principle of "If you can't dazzle them with your brilliance, baffle them with B.S."

I did manage to get the job based on an ammonia system in a pretty deep vacuum.

I feel your pain on the "local expert" not knowing but will try anything. I have gone behind a number of these experts and do get to make some nice money getting the system to operate correctly.

The small owner thinks he is getting a good deal because he can get a local contractor to "design" and install a system without paying to have an engineer do the design. As a minimum, the owner needs to hire an ammonia experience consultating engineer to review the designs and protect the owners interest. The engineer will be working for the owner and his only interest is to see the owner receives a properly designed system that meets his requirements.

Having been in the sales side of the business, the small contractor, often does not have an engineer and will depend on his suppliers to "properly design" each piece of equipment. Only the contractor, is looking at how all of the pieces fit together...or may not fit together.

I do know several smaller contractors that have people that are very capable of doing proper ammonia design, but for everyone that has the experience, there are probably 10 that do not have the experience.

Ken

[US Iceman]

...there has been some work done at lower temperatures and the use of a "slurry" in the Evaporator.

CO2 slurry? Wouldn't that require very precise control of the pressure? It sounds interesting.

I have gone behind a number of these experts and do get to make some nice money getting the system to operate correctly.

Ohhh, there's definitely money to be made doing this. It does take a completely frustrated owner that has been severely burned to listen though.

The problems all stem from this:

He operated on the principle of "If you can't dazzle them with your brilliance, baffle them with B.S."

and willingness to do this...

...will depend on his suppliers to "properly design" the system.

(I changed this slightly)

and this,

...for everyone that has the experience, there are probably 10 that do not have the experience.

Refrigeration is refrigeration. The components change as do the way systems can be configured, but the operating principles are all the same.

A lot of people are mystified by CO2, since it has not been used very much in the last 60 years or so there is not much of a developed basic knowledge. It's just another refrigerant that has some funny characteristics.

[smpsmp45]

I could not come back to this one earlier.

But we could convince the customer with R 404A. The main reason being almost operator free stsem , Simple & Importantly reliable system, Less space. ( we were taling about Monoblock units ) & no Plant room. cooling towers etc. Power , we worked out was not much less with water cooled Ammonia System. One has to add Cooling tower fans. Water pumps, Pumps for Compressor Head cooling, & even Liquid Ammonia Pump Power. Here I am yet to see a ammonia plant which does not smell. The Shaft seal has been the biggest issue for all the time.

It was almost 3000 Tons cold Store. With Ammonia Screw System / Or even Recip system for -25 deg c against 5 nos 50 HP aircooled wall mounted R 404a Units. It was more on practical aspects more than theory. The customer had few cold stores with Ammonia & he know the problems. Only point was whether to go in for Monoblock units for such a large cold store.

[US Iceman]

Does India have a mandatory requirement for operating people to be on-site when ammonia is used as a refrigerant?

The customer had few cold stores with Ammonia & he know the problems.

What were the problems? (besides the shaft seals and ammonia leaks?)

[smpsmp45]

To be very frank, the compressors are made as per very old designs ( Sabroe & The JV was in 1980). Still the same design is being used. There are hardly any other compressors available ( I am talking about Ammonia) , The Coils made ( except by 1/2 companies) are again age old designs). Comparatively, the ref units which are are IMPORTING come with high reliability, Sleek designs & absolute great in performance.

If you have an Ammonia system , you need operators to close the valves ( The systems are I would say semi Automatic type yet due to the costs), . The electrical supply is always a big issue & hence operator is a must. That is even needed for R 404A systems, but there he only monitors & does not have to run around.

Now a days ofcourse things are improving & may be some time to come, we shall have a tough task in our hands to convince the cliient on R 404A

[Samarjit Sen]

Ken and Mike,

In India you just have to know what is a compressor etc. and you become an authority. As smpsmp45 says, that the technology available in ammonia in our country is very old. I remember, Mike thatn once you stated that the technology appears to be 60 years old. You are right.

Now coming back to smpssmps45, if the storage chambers are large then please do not install monoblock unit nor advice your client for the same. It will not produce the required temperature. If I am not wrong, some time back you had put a similar post also.

[US Iceman]

Hi guys,

If a "*****" system can be installed to run unattended, there is no reason an ammonia system cannot be installed also to be fully automatic. Unless there are some code restrictions in your local areas.

I cannot think of any reason why an ammonia system could not be designed to be fully automatic.

A manually operated ammonia system is (or should be) a thing of the past.

One thing I think is very important: the technology used should be very simple and easily understood for correct operation.

Ammonia systems do NOT have to be complicated or a big mystery!

(Although many were, and some still are being installed like this)

I love ammonia!

[smpsmp45]

Uptill now we have done atleast 10 large cold stores with capacity over 300o Pallet spaces using such Monoblock units & the clients were very happy. They do work. Even in Gulf we had done large cold stores using such equipments. Our experience is too good with such units.

Though I agree with US ICeman that Ammonia systems are not very complicated or A big mystery, the practical experience is different atleast in India.

[smpsmp45]

Again on the shft seal leaks. When we had used Imported Shaft seals , the leaks were almost NIL. But when the manufacturer is forced to use local shaft seals, the problems start & they never end.

When we first Installed Monoblock units in one factory which had ammonia system for almost 10 years, we receiveda sort of complaint that we can not chrage the system on daily basis, ( which they were doing in Ammonia plants!!!)

But at the same , time, things are improving here & better shaft seals are available.

[Samarjit Sen]

Hello smpsmp45,

Could you please let me know the dimensions of the Cold Storages wherein you had installed the monoblock units ? Generally monoblock units have a vary limited air throw, and as such there are all the possibilities of air locks being formed. These Cold Storages are meant for what products.

Thank you,

[TXiceman]

I was slightly involved in a large R507 system and it was a nightmare. This customer had historically put in ammonia systems, but since this plant was next to the corporate headquarters they wanted a "friendly" refrigerant. To start with the initial refrigerant charge was in excess of $250,000.00 (US). The initial vacuum dehydration was very time consuming and we had one heck of a time getting the system dried out and to hold a suitable vacuum for a "*****" system.

The system would have been much less $$$$ to put in with ammonia then R507. Operating cost is less on ammonia and the refrigerant cost is much less.

Any refrigeration system can be automated, but any larger system does need a person trained in the operation and maintenance. Just by putting in a "*****" system, it will not make it operator-free.

I can not in good conscience recommend anyone use "*****" on any larger central plant system.

Ken

[Samarjit Sen]

Hi Ken,

You have the expertise of ammonia system, which we in our country do not have. If you see one of the ammonia systems you will agree with me. Here in large Cold Storages, ammonia is being used and due to bad design, the plant does not operate for long.
I agree that ammonia is very good and if the systems are designed properly, it can be very effective and efficient.

[smpsmp45]

The Larest cold store was 60 x 50 x 11 mt high & was using 5 nos 60 HP units. Others are typically 20 x 45 x 12 with 5 nos 40 HP units. & few are 20 x 30 x 8 m with 1 No 50 HP units. all are for -25 deg c.

[Philip]

ammonia compared to 404 is much cheaper but high risk to the one handling it.i suggest to use r507 as it is as efficient as the r404 and have a better blend.these two refrigerant(r404a&r507) are both good for low temp and mid temp application. hope this will give you better comparison.good luck

[HallsEngineer]

Ammonia is probably THE best refrigerant for me. If there's a small leak it tells you, you dont have to go looking fo hours. Its VERY efficient. Halls recently installed a screw water chiller on ammonia with an air cooled condenser. It works very well with inverter drive systems on fans and compressors. If you put the plant outdoors it has a lot less regulations (bad thing?). But no its not impossible to do just not cheap.

[suny]

Hi Brian Chapin,

You are quite right and I do accept the fact. The problem here is that most or rather all the Ammonia Plants are basically for Potato Cold Storages or some thing like it. The user in order to save money catches hold of a technician who may have no knowledge of refrigeration and may had worked with some one in an ammonia plant. He becomes the authority and gives the consultancy as well as install the plant. He gets local make compressor and equipments from those people who are willing to pay him a commission. He installs he plant. The user feels that keeping a man for operation would be expensive , so he prefers to keep some one who has no experience in this field. The result is that after a couple of years the complete plant breaks down.

I have visited a large number of plants of ammonia and on seeing the plant ( or rather the contraption ) was surprised that hoe did it operate. When I tell the user that he has to scrap the plant and install a new one which besides giving him an efficient performance will also reduce his power consumption. The reply is the same, " will let you know ". The matter ends there and in comes the so called authority and starts all over again.

So what I had said was sheer out of seeing the situation here. I would love to install a sample plant of ammonia, provided one is willing to pay. Am trying to locate one.

Hi! Dear Samarjit

I do not know how to approve what you have quoted above. This is what we in Sri Lanka are facing in NH3 plants with this type small time operators becoming big time installers of new plants by hand picking all sorts of used compressors, discarded condensers & accessories with out any proper balancing of the whole plant.

Finally the whole plant fails. This is what has happened to my friend.

Suny

[R. sivakumar]

usage of R44A or R717 is based on its application, size of the plant, loaction, condensing teperatures etc.,
I think we need to analyze all these aspects while selecting the refrigerant. Out of all these in todays scenario, the location of the plant is most determint to select the refrigerant. The quality of installation and quality maintenece are very vital for NH3 as any leaks in a crowded area can be fatal.

in my opinion we cannot generalize it by saying 717 is good or 404a better. if you can send me any specific data of the requirement i can clearly tell you which refrigerant suits (better word to use) to the particular project.

regards,

Sivakumar R Nair
email: siva@sivarefconsultant.com
india - +919980088268

[cduque]

My opinion based in many years of experience is:
. R404a: lower investment, lower need for permanent surveillance: better on small or comercial applications
. R717: lower costs in energy, exploration and maintenance: better on industrial or big installations

[Grizzly]

My opinion based in many years of experience is:
. R404a: lower investment, lower need for permanent surveillance: better on small or comercial applications
. R717: lower costs in energy, exploration and maintenance: better on industrial or big installations

And your reason for answering this 4 year old post is?
Grizzly

[TXiceman]

I have designed ammonia systems as low as 50 HP. In any case, yo need someone qualified if refrigeration to work on them. Now a normal A/C tech can probably do OK on a r404 system, but he will be lost on ammonia.

Another issue on 404 is that it is not a pure single component refrigerant but is a blend and you do have a temperature glide (all 400 series fall into this category). You do not get condensing or evaporation at a single temperature point. There for yo will have a varying mixture at different pints in the system and depending on where you leak, you may leak more of component A, or B or C. Now when you have to add refrigerant, which do you add? You recharge with liquid to get them all and you not longer have a balanced mixture to match virgin R404. Over time, you will loose capacity due to the different mixture.

For this reason, I can never recommend any 400 series except for the smaller packaged systems. If it is a larger system, go to R5057.

Now Europe is chasing away R134, so what will be used to keep the beer cold.

Ken

[Jason NH3]

I agree 100% with Brian, I have had similar experiences with a 10,000 lb. R22 plant, IF the plant spent thousands of dollars leak checking the system on a routine basis then there refrigerant additions were relatively low for a one year period, probably less than 500 lbs. After a years time they became tired of paying our company for the leak checks so they stopped. In one years time they added 5-6,000 lbs of refrigerant. Three hours north I have a similar sized facility running R717- they haven't added refrigerant in over 5 years. With the cost of "*****" refrigerants it is a no brainer for me. We are doing quite a bit of work now with R744 (CO2). I really see this becoming a very popular refrigerant for such applications as this thread.

[oldesky]

Both systems have their place. Why you would use R404a instead of R507 escapes me.R 507 is better in just about everyway. Testing of topping up R404a systems with R507 has shown positive results with increased efficiency at different percentages across the range. Amonia has a limited place. I note someone compared the difference in refrigerant priceof R507 to Ammonia. Ammonia plants are fare more expensive to install and operate.Even a $250,000 gas charge starts to look good if you consider the cost of a plant operator. Yes but what if all the gas leaks out? I hear you ask. I remember a few years ago in a melbourne inner suburb an industrial ammonia system had a major leak. Everybody within a one kilometre radius of the plant was evacuated. I can assure you the cost was considerably more than $250,000. In saying that ammonia has a place in large plants away from populated areas.