Compressed Air Dryers: Will -70 deg C Pressure Dew Point Truly Makes A Difference Than -40 deg C?

Compressed air dryers, regardless of type, are rated using pressure dew point or PDP. PDP is the temperature to which compressed air can be cooled without condensation of the water vapor initially contained in the air. Since it depends upon the final compressed air pressure, its value varies. If pressure drops, the PDP drops with it.

But the questions that really matter to engineers, especially to the users, are: How much water must be removed from compressed air? What PDP must be specified and what type of dryer must be chosen?

The answers to these questions depend on the area of application of compressed air. If the application is for pneumatic tools, spray painting, or conveyance air, then DIN ISO 8573-1 recommends Class 4 with a maximum residual water content of 5.953 grams of water per cubic meter of compressed which is equivalent to 3 deg C PDP. A conventional refrigerant for these applications might be selected. However, DIN ISO 8573-1 gives a wide Class 1 to 3 recommendation for applications such as breathing air, breweries, dairies, instrument air, and pharmaceutical industry. This is equivalent to -20 deg C to -70 deg C PDP, the latter being Class 1. This wide gap is a challenge to engineers because a -70 deg C PDP regenerative drier is perhaps a few thousands of dollars more expensive than a -20 deg C PDP one. Most novice and conservative engineers will probably select the lowest recommended PDP for safety and hence will select an expensive regenerative dryer, perhaps heated and blower purged. On the other hand, more experienced engineers will probably pick a relatively economical -40 PDP regenerative dryer with dew point analyzer or monitor for the same application. These engineers likely know that the moisture in air might exceed what a -40 DPD dryer can handle especially in cold environments. Why still go with the higher PDP? The answer is pretty much straightforward. As the PDP goes very low the decline in the maximum moisture that the air can handle is relatively small. A rule of thumb is for every 20 deg F (11 deg C) drop, the moisture drops by a half. This means that if the moisture content at -40 deg C PDP is 0.117 grams per cubic meter, then at -51 dec C PDP, the moisture will be around 0.058 grams per cubic meter and so on. This leads to the fact that the moisture content in air will never reach zero no matter how low the PDP becomes. Hence, to these engineers the small difference in the moisture content between -40 deg C and -70 deg C PDP is not worthy of the additional thousands of dollars in initial and operating costs the lower PDP dryer entails.

Yang Yong-Eun did it! Who will be the next one?

Many believed that it is only a matter of time than an Asian male golfer will win a major title in golf, a sports considered for the elite. Darn, they were right. Korean Yang Yong-Eun became the first Asian-born pro golfer to win a PGA tour. And the manner he won it was even astonishing; he came from behind and beat Tiger Woods. Yes, he did beat the greatest golfer of the modern era who was atop the leadboard going into the final round!

Now the question is, among the many skilled Asian pro golfers, who will follow Yang’s lead? Name your choice.

1. Jeev Milkha Singh, India
2. Thongchai Jaidee, Thailand
3. K.J. Choi, Korea
4. Prayad Marksaeng, Thailand
5. Charlie Wi, Korea
6. Lin Wen-Tang, Thailand
7. Jyoti Randhawa, India
8. Bae Sang-moon, Korea
9. Hur Suk-ho, Korea
10. Noh Seung-yul, Korea
11. Gaganjeet Bhullar, India
12. Chapchai Nirat, Thailand
13. Liang Wen-Chong, China
14. Lam Chih Bing, Singapore
15. Thaworn Wirachant, Thailand,
16. Lee Dong-hwan, Korea
17. Arjun Atwal, India
18. Chinnarat Phadungsil, Thailand
19. Juvic Pangusan, Philippines
20. Kin Jung-Tae, Korea

Things to Remember in Specifying Fire Water Pumps: A Simple Guide to Specification Writer

When writing specifications and material requisitions for fire water pumps or any other mechanical equipment for vendor proposal and eventually for purchase, the technical writer should focus first on specifying the basic requirements given below before going into more technical details about the equipment. The reason being is that detailed technical requirements are usually prepared and written in a separate pump or equipment data sheets that are usually attached to the requisition. There is no need to write those requirements in the requisition anew unless some major technical issues are really needed to be stressed or emphasized.

Specify the quantity of fire water pump units required, pump type, type of driver (electric motor, diesel engine, or steam turbine), etc. Although these requirements are most probably already included in the pump data sheets, it is always good to mention them in the material requisition under, let’s say, the general requirements section. For multiple fire pump units, it is good to mention how many units will be driven by electric motor and how many will be driven by diesel engine or steam turbine.

Specify the required codes and standards for the design of the pumps. Most clients demands that their fire water pumps shall comply with National Fire Protection Association 20 or NFPA 20 (usually for insurance purposes). Local codes and client’s standards are also usually a requirement. If plenty of codes and standards are to be used, it is important to state the order of precedence of these standards or codes in the requisition to avoid confusion down the road. It is also a good idea to require vendor to immediately inform you for any ambiguities found among the required codes and standards. In doing so, a resolution can be done immediately before any purchase are made.

Completely specify the vendor’s scope of supply. Aside from the fire pump unit itself, whether it is a simple pump unit - a pump, its driver and controller mounted on a baseplate - or a complete package system with additional ancillaries such as pressure sensing lines, fittings, and valves, fuel tanks, etc. which may be placed on a skid or housed in a sound enclosure if noise emission is of utmost importance, specifying some if not all of the following items is always a good practice:

Lifting Tools. Lifting tools or devices that may be needed to lift your units during transport to site and during installation must always be considered. If the delivery and installation of the units are to be shouldered by the vendor, lifting devices that are needed in these services should also be in the vendor’s scope. However in some instances, installation and commissioning is done by the client or the purchaser. In this case, it is always good to clearly specify who will supply these items in your requisition.

Special Tools. Especially for packaged systems, where several ancillaries are procured and most of them are put together at site, the need of special tools must be considered. Inclusion of this item in the material requisition, whether as an absolute requirement or as an option, is not a bad idea as it can always be deleted from the vendor’s scope if not needed during technical clarification.

Spare Parts. Capital and commissioning spare parts and spare parts for normal operation are almost always proposed by the vendors and included in their technical proposal. If your client had had or used similar fire pumps units before, you might want to ask their advice about which spare parts are to be eventually procured as they might still have spare parts available in their inventory or shop, not to mention that they might have a good knowledge about which spares are likely to be frequently replaced.

Field or Site Services. Even if your client’s engineers are very well versed in installation and commissioning of fire pump units, it is always a good idea to have someone from the pump supplier side to oversee or supervise the installation and commissioning works. It might cost your client a few more hundreds of dollars, but it is a worthwhile expenditure because it is vital to safeguard guarantees and to bring the responsibility to the vendor when problems occur down the road caused by faulty installation or commissioning.

Documentation. Perhaps one of the most important items in the material requisition is the documentation that the vendors should provide you and/or your client during the pre- and post-order stages. Without them or lack of them, technical evaluation is usually poor. If they are omitted in the requisition, chances are the successful vendors will overcharge you or your client for any documents that are demanded after order is placed. Some important documentation are equipment data sheets, technical literatures and manuals, utility requirements, performance curves, control description and philosophy, general assembly drawings, sectional and layout drawings, P&I Ds, list of deviations to applicable codes and standards, QS plan, flange loading data, test curves, etc.

Packing and Shipping. It is always a good idea to include this item in the requisition to ensure the integrity of the fire pump units when they reach the site. Marshall’s Law

Concepcion - Luevano Fight: Scrutinizing Jay Nady

“No one is perfect”. This saying is very true. Unfortunately boxing referees, where a single mistake may determine a fate of a boxer, are not exempted to this rule. But what if a boxing referee errs as often as the Hollywood stars change partners? Would you ever trust his officiating again? Case in point: Jay Nady.

Jay Nady was the third man in the Bernabe Concepcion – Steven Luevano title fight in the much hyped Pinoy Power 2 PPV fight. Nady disqualified Concepcion after the 7th round for throwing late punches that knocked his opponent out. Many boxing experts say that Nady’s call was right. Few however, still insist that the illegal blows thrown by Concepcion, whether the Filipino pugilist unleashed those shots intentionally or not or whether he heard the bell or not, could have been prevented if Nady timely jumped in between the fighters after the bell sounded. Are these few boxing aficionados unfairly judging the veteran referee? Maybe or maybe not. However, the fact that is as clear as spring water is Nady had had many controversial calls in several fights in the past. Here are some in no specific order:

Roy Jones Jr – John Ruiz (1st round): Nady spewed six warnings to Ruiz when no apparent fouls were being committed. When Nady was breaking the fighters up for the second time, he told Ruiz “You hit him twice low, bring your punches up”. Ruiz tried to argue but Nady immediately retorted “No, you listen to me. They were low”.

Marco Antonio Barrera – Juan Manual Marquez (7th round): Barrera clearly knocked Marquez down with a crisp right straight as the round concluded. But, Nady surprisingly ruled it as a slip and deducted a pivotal one point from Barrera for hitting after the bell. Nady could have easily prevented Barrera for hitting Marquez when the latter was down if he was close to the action.

Kendall Holt – Ricardo Torres 2 (1st round): After knocking Holt down in the opening seconds of the first round, Torres swarmed Holt with a flurry of punches in an effort to end the fight and a left hook put Holt to the canvass anew. Nady was a bit late to react and as soon as Holt regained his feet, Torres landed one more left hook which was a clear foul but startlingly not acknowledged by the veteran referee.

Edwin Cassiani - Luiz Collazo (3rd round): Cassiani uncorked several combinations on Collazo midway of the third round that noticeably dazed the American. Collazo was still on his feet; perhaps the ropes were holding him up, when Nady hastily waved the fight off. Many believed that Nady over reacted and that the stoppage was pre-mature.

Butterbean – Peter McNeeley (Pre-fight referee instructions): During the referee instructions and touching of gloves, Nady gaved nothing, obviously he already made his instructions at each fighter’s dressing room, except “Do you have any questions? Obey my commands”. When one of McNeeley’s corner men asked him “Where’s the (Butterbean’s) beltline ref? Where’s the beltline there?” Nady retorted “I see his beltline”. The same corner man responded “Well, it’s a little bit high”. Nady said haughtily to the guy “Stand back. Go back to your corner.” He then asked the boxer to touch gloves and told the same corner man to his face “And don’t tell me how to do my job again.” While many thought that the event was a storm in a teacup, others maintained that Nady should have answered the valid question but chose not to. What he showed was the arrogant and close-minded side of him.

In all of these fights, not to mention the Tszyu-Judah, Taylor-Hopkins 2 and Corley-Flores fights, Nady proved his inconsistency as the third man inside the ring. And in the recently concluded Concepcion-Luevano fight, he proved it to the boxing world once again. He might be a hall a famer referee, but at the same time, he will probably become the most controversial referee in America ever. (photo: Referee Jay Nady)