Reprinted from the ACJ - July, 1999
A High Pressure system sits over mid-America. Temperatures soar. Auto cooling systems overheat. Boyle's Law works it's magic and cooling system pressure increases. Hoses blow, tubes split and coolant sprays. Another victim of excess pressure. You may be driving it. You may be working on it. Stress is right there to continually ask "is it ready yet?'. Kid comes home in a cop car and your spouse presses you to "talk to your son".
He says "yeah Dad, but everyone's doing it". Another hapless victim of peer pressure. This time Boyle's law has nothing to do with it but your Blood Pressure is rising fast. If tubes split or hoses blow, you are in trouble. Another victim of High Blood Pressure, or Hypertension as it is known in the trades. Over fifty million people in this country suffer with Hypertension. Fully one third of them don't know it, sometimes until it is too late. Your body's `blown hoses' and `split tubes' take the names Stroke, Heart Attack, and Kidney Failure.
Blood Pressure is important, try living without it. But, too much of a good thing and we have trouble. Normal Blood Pressure is `120 over 80'. Easy for me to say. Harder to explain. Like any closed system with a pump in it, be it cooling system or circulatory system, there is pressure in the `lines'. The higher the line pressure the harder the pump has to work, the faster it will wear out. In cars we encourage that. Water pump work is easy money. In circulatory systems, the work is not so easy, still lots of money.
That Blood Pressure test, with the cuff around your arm, measures two different pressures in terms of how many millimeters of Mercury (mm Hg) the pressure displaces. The first pressure measured; and the top number in the `something over something' reading, is called the Systolic Pressure. This is the highest pressure resulting in your arteries when your heart contracts and forces the blood through your tubes. If this number gets above 130mm Hg it can mean you are at risk for heart attack or stroke. The second pressure measured, or under number, is a Diastolic Pressure. That is the resting pressure in your arteries between heart beats. If this exceeds 85mm Hg, more bad news, possible aneurysm or kidney failure.
There are many reasons your blood pressure may go up. Just going to the doctor can cause your blood pressure to rise (so called White Coat Hypertension), so can angry customers, misbehaving kids, and nasty traffic. These temporary rises do not necessarily mean trouble. Experts consider three consecutive high readings as a hypertension condition. Our genetic makeup plays a large part in our blood pressure level, but certain risk factors add to the problem. Excessive weight, eating a high fat and/or salt diet, alcohol abuse, smoking, lack of exercise and diabetes all contribute to elevated blood pressure.
I'm sure you see it coming. The answer to the question, `How to control High Blood Pressure?'. Step one, lifestyle changes. Give up all that fun risk factor behavior we described. Reduce your weight, eat fruits and vegetables, don't drink or smoke, and exercise regularly. This is the first `prescription' given to people with hypertension. But it is also the recommended course of action for folks in the twilight zone between the normal reading of 120/80 and the high reading of 130/85. This zone is known as the `high normal' range. OK, so you are bored silly, but healthy, and your blood pressure still registers too high. Your doctor will now look at prescribing medication to lower it further, and stabilize it in the normal range.
As I said before, fully one third of people with hypertension don't realize they have it. So, get your blood pressure checked. Please risk the `White Coat Hypertension' and go to your doctor. Cooling system and circulatory systems may be similar but the testing equipment is not. I modified our pressure tester here at Johnson and darn near popped my eyeballs out. I did find out though, I'm freeze protected to - 25F.
The above article was written by David M. Brown, Chief Engineer of Johnson Manufacturing Company, Inc. and is published by JOHNSON with the expressed approval of the National Automotive Radiator Service Association and the Automotive Cooling Journal. Other reproduction or distribution of this information is forbidden without the written consent of JOHNSON and NARSA/ACJ. All rights reserved.
JOHNSON MANUFACTURING COMPANY
114 Lost Grove Road / PO Box 96 / Princeton, Iowa 52768-0096
Phone 563-289-5123 or Fax 563-289-3825