Feature

Benefit

Each cover comes standard with four tie-downs equipped with locking child resistant safety latches. To assure the integrity and prevent the straps from ripping out (perhaps from high winds), the straps are sewn into the cover in four places, including the skirt. This makes them virtually tear-proof.

Besides aiding in keeping out unwanted visitors, the tie-downs, when properly used help to prevent strong winds from blowing off the cover. There is also the option of   additional tie-downs.

The "locking latches" are molded after the quick release buckles found on sports equipment and have been specifically designed for spas! Each NMF Fastener may be locked down individually. They are quickly installed with three stainless steel screws (provided).

The zippers are one of the lesser important parts of a cover.  However if anyone ever steps on your cover causing the foam to bow you'll want to remove and turn over the inner foam core. For this reason we only use zippers designed to maintain their "zipping" ability for years.. Besides having the largest teeth available (6mm), they're rust and chemical corrosion proof. And of coarse they're quadruple stitched for added strength.

With the entire cover being double stitched together, the thread is also an important aspect to consider (some cover manufacturers heat seal  their vinyl together, but the seams tend to become very brittle in the hot sun and freezing cold).

The thread used in our covers is a 93#,  UV resistant, bonded, Dacron Polyester thread. The polyester part is what's important, unlike cotton thread (or cotton wound polyester) it won't rot out in a short period of time, and the UV resistance prevents any degradation from the sun. "Bonded" means that it's actually water tight and can't absorb mildew causing moisture. The 93# is the weight of the thread and the entire cover is completely double stitched.

"Marine Grade Vinyl" was developed for the harsh climates of boating and the awning industry. To be classified as a marine grade, the vinyl has to meet certain requirements (whether these requirements are exceeded or not is another story). The vinyl used in our covers exceed all specified requirements of both "Marine Grade Vinyl", and "Premium Grade Vinyl"!

The following are the specifications of the vinyl used in our covers (helpful for making any comparisons);

Unlike some covers where the vinyl cover is heat sealed together, another important feature of these covers is that they are completely double sewn together with the highest quality thread. Heat sealed seams become very brittle in the hot sun and freezing cold.

The vinyl in these covers, besides being the thickest in the industry, also has mildew inhibitors, UV stabilized coloring to prevent fading, increased resistance to chlorine and bromine and is available in 10 colors (see below).

The skirt of a cover is another of the many important parts. It needs to properly protect the lip of your spa from the damaging rays of the sun, and be strong enough to use for lifting your cover. These cover's skirts are double stitched into the cover for strength, and gusseted to provide the best protection! One piece continuous skirts, which are easier to manufacture, have many inherent problems as compared to skirts that are gusseted (also called "slited"). Gusseted skirts will hang much straighter and have less tendency to bunch-up under the cover, preventing a proper seal between the cover and the spa.

As the sun beats down on a cover, extreme heat can build up between the skirt and the outer lip of the spa. This intense heat can actually damage the outer lip of the spa. A gusseted skirt allows this heat to escape, preventing heat damage from occurring. The skirts are double sewn into the cover for extra strength  and strong enough to lift even the heaviest of covers.

Standard nylon webbing handle

Optional vinyl covered handle.

Unlike the handles on many covers which tend to be a great weak point, these spa cover handles have been designed and engineered to be one of the strongest! Handles are great when the cover is new, but over a long period of time most covers eventually get a bit heavier. Cover handles, having such a small attachment area can be easily torn off, sometimes tearing the cover. Our cover's handles are made of extremely strong, 1-1/2" wide nylon webbing. Additional stitching, and internal reinforcing make them some of the strongest available. One of the many options offered, is to have the nylon handles vinyl covered.

On the underside of the cover there are two additional handles attached to the continuous "hinge seal". These handles help in maneuvering the cover on and off the spa in tight areas.

Running the entire length of each piece of foam, along the hinge is a 2½" wide, 20 gauge galvanized steel C-channel support beam. This is the heaviest gauge (thickest) reinforcement beam used in the industry, others tend to be 22 to 26 gauge. Galvanized steel is used for it's increases strength over aluminum, and also because of it's greater resistance to chemicals (chlorine and bromine). C-channel is much stronger than lesser expensive T-bar others may use.

If the possibility of this C-channel rusting has been made a concern to you, it really shouldn't be. The only way for this C-channel to rust is if the vapor barrier surrounding the foam is broken. If this happens the foam core of a cover will absorb water (getting heavier and heavier) long before the C-channel loses any integrity.

One of the options offered on these covers is to double wrap the foam core with a second layer of polyethylene sheeting. This is something no other manufacturer offers and we highly recommend it due to the following.

Covers have a small hole on the bottom side of the vinyl covering to allow any accumulated water and condensation to drain out. As much as this is an absolute necessity, it also allows evaporating chemicals to rise up into the covers interior (needless to say covers with an open mesh bottom are the worst). Over a long period of time these chemicals can start deteriorating the vapor barrier to a point where it becomes porous. The porosity then allows steam and evaporating water to penetrate into the foam insulating cores. One day science will probably develop a better vapor barrier (although those wanting to sell lots of covers may not use it), but until then doubling up the polyethylene sheeting will extend the life of your cover.

The covers foam core is the "back bone" of every spa cover. Not only is it the main insulating factor, it also provides the strength needed for years of use. One of the important features of our foam is that it's a virgin foam, rather than recycled. While both may have the same insulating value, recycled foam doesn't have nearly the strength as the virgin foam we use.

The foam core of our Deluxe spa covers are a 1.5 pound density, metal reinforced, EPS (expanded polystyrene) foam , tapered from 4" to 2". The foam core of our Extreme spa covers are is a 1 pound density, metal reinforced, EPS (expanded polystyrene) foam , tapered from 6" to 4". The taper is necessary to allow accumulated water to easily run off. Many older, and some cheap covers are made of a flat foam which will allow water to puddle,causing the cover to sag, allowing more water to puddle, eventually breaking the cover.

Please note, these measurements are the true measurement of the foam itself. It is not a nominal measurement, nor does it include the thickness of the vinyl or vapor wrap (you'd be surprised how many others don't use a "true" measurement, and add in thickness of the other materials used).

Foam density refers to the weight of a cubic foot of foam. A 1.5 lb. density is generally the ideal for a 4" thick cover. It has excellent strength and insulating ability, yet is light enough to maneuver on and off your spa. Lesser densities are NOT advised for a cover of this thickness due to their lack of strength. With our 6" thick cover, a 1 pound density is more than enough. It provide almost 50% more insulation value over our 4" cover, is stronger, yet  is the same weight. Higher foam densities have additional strength, but only slightly more insulating ability. One of the many options we offer is upgrading to a higher density foam if additional strength is needed.

With the standard 1 pound density foam cores, the  Extreme spa covers have a minimum insulation value of R-21. The optional 1-1/2 pound density foam achieves an even higher R-value!

The insulating core of almost all spa covers is EPS (Expanded Polystyrene). The insulating value of this product is very specific, and is listed in the table below. Please note, the R-value shown is for 1 inch of thickness.

Foam Density	R-Value/in.
1.0	3.85
1.25	4.0
1.5	4.17
2.0	4.35

Remember, all EPS foam of equal density has the same R-value!

---

"What is the R-value of your cover"? While this is the most common question asked when comparing covers, the answer can be the most deceptive. The following, though rather lengthy, explains insulation and R-value. The short answer to the R-value of our covers though, is R-14½ with the Deluxe spa cover and R-21¼ with the Extreme spa cover.

R-value describes a material's resistance to the flow of heat. The higher the R-value, the slower heat will travel or conduct through a material. Better insulating materials tend to have better R-values.

Heat flows by three mechanisms: conduction, convection, and radiation;

Conduction is the molecule-to-molecule transfer of kinetic energy (one molecule becomes energized and, in turn, energizes adjacent molecules). A cast-iron skillet handle heats up because of conduction through the metal.

Convection is the transfer of heat by physically moving the molecules from one place to another. Hot air rises; heated water thermosiphons; forced-air heating systems work by moving hot air from one place to another.

Radiation is the transfer of heat through space via electromagnetic waves (radiant energy). A campfire can warm you even if there is wind between you and the fire, because radiation is not affected by air.

R-values by definition, only measures an insulation's ability to resist heat loss by CONDUCTION.

The above's relationship to spas is this; heat from the spa water rises by convection and radiation. As it rises it heats the underside of the cover, then moves through the cover by conduction. Increasing the covers R-value reduces, or slows the rate of conduction. There are also two ways to reduce the rate of convection, the first being a floating blanket, the second being our optional exclusive Reflex Energy Shield used for the covers underside material.

R-value is a term coined by the FTC in response to a need for a way to compare the relative effectiveness of various forms of insulation. R-values are measured by testing laboratories (ASTM), usually in something called a guarded hot box. As air within the test hot box is heated, convection takes place, causing the heat to rise. As the heat rises it warms the underside of the foam where upon conduction of the heat through the foam begins. The R-value is the ability of the foam (or other material being tested) to slow this conduction. Heat flow through the foam is calculated by keeping one side of the material at a constant temperature, say 90°F (32 °C), and measuring how much supplemental energy is required to keep the other side of the material at a different constant temperature, say 50°F (10°.C)--

Various industries are required to have their products R-value tested by ASTM under very exact testing perimeters. One of the parameters of this test is the temperature at which guarded hot box is heated to, AND the temperature the other side of the test material is kept at. Changing either of these temperatures will result in different R-value results. Once again, certain industries are required to use ASTM testing procedure and parameters. For these industries, when they list their products R-value (such as R-20) it's understood that the difference in temperatures of the testing procedure is 40 degrees (or R-20 @ 40º). It's also acceptable to list another R-value AS LONG as the temperature difference is listed ALSO (i.e. R-40 @ 20º). Here's the relationship to spa covers. SPA COVERS ARE NOT IN AN INDUSTRY REQUIRED TO HAVE R-VALUES TESTED ACCORDING TO ASTM STANDARDS! When comparing the R-value of a hot tub or spa covers it's important to ask what temperature difference the R-value was calculated at. Our covers are rated at a temperature difference of 40º (i.e. R-21 @ 40º).

The hinge is one of the most worked parts of a cover, and on cheap covers one of the first things to deteriorate thereby letting steam and heat escape. First of all, our covers do have a hinge (they're not simply two half covers sewn together), the hinge is constructed of the same high quality vinyl as the rest of the covers covering. Our hinge is also four layers thick and is quadruple stitched for the longest life available.

With the current trend of cover lifting devises (which we highly believe in) the hinge is one of the most worked parts of a cover. This hinge is constructed of the same high quality vinyl as the rest of the outer cover. It is not simply two halves of the cover sewn together, but is a one piece hinge, double stitched into each half of the cover. One of the options available is additionally reinforcing the hinge by adding an extra layer consisting of the same 1-1/2" wide nylon webbing the handles are made from. This upgrade consists of a strip of nylon webbing running the entire length of the hinge! While other covers hinges are their weakest point, this nylon webbing reinforcement makes these hinges the absolute strongest possible!

These covers have a continuous insulated "hinge seal" to prevent heat from escaping from an area most people don't even think about. Most other covers have what are called "fingers" or "steam sealers" (below). These are two pads that are placed on the underside of the cover, at the ends, between the two halves to prevent steam and heat from escaping when the cover is installed on your spa. If you turn one of these covers upside-down you'll actually see that they also push the two insulating halves apart (below), leaving as large as a one inch gap between the two halves. This is equal to having a hole the size of a basket ball in your cover, your INSULATING cover!

The underside material of the cover that faces the spa's water takes the most abuse. It's also the first line of defense in preventing chemical damage and moisture infiltration, and must be durable enough to withstand the constant dragging from removing the cover from the spa. these covers use a12oz double laminated, tight mesh reinforced, chemical and ozone resistant scrim. This material is so strong (it's constructed similarly to rip-stop- nylon) that it's used internally throughout the cover to reinforce the double stitching.

As an option, the scrim can be substituted with Reflex Energy Shield, a 12 oz scrim, coated with a highly reflective, woven metallic material. One of the ways heat is lost is that it radiates out in waves (see above on R-value for a full explanation on insulation value and heat loss). The Reflex Energy Shield gives our spa covers an advantages over other spa covers. The reflective nature of the Reflex Energy Shield yields a reflecting dish effect that bounces these heat waves back down into the water, thereby increasing the cover's insulating ability.

Please note, excessive chemical use in the spa can lead to the woven metallic material "blistering" from the scrim. Excessive chemicals are the only thing to cause this, and blistering or bubbling is not covered under warranty. Covers with Reflex Energy Shield should be removed from the spa for a minimum of 20 minutes when shocking.

ASTM (American Society of Testing: and Materials) has developed a standard for both swimming pool and Spa Covers. This Standard, ASTM F 1346-91, establishes three separate cover classifications;

In order for a spa cover to meet the requirements for a "Manual Safety Spa Cover" it must meet certain requirements which include performance tests and labeling requirements.  Covers must be able to pass tests such as Static Load Tests for weight support, Perimeter Deflection Tests for entry or entrapment between the cover and the side of the spa and Surface Drainage Tests to see if a dangerous amount of rain could collect on the covers surface. There are also requirements to include labeling in consumer information (such as the warranty), and on the cover itself. Labeling must contain the proper warnings, and identify the product as a safety cover.

Non-safety covers can meet ASTM standards if they comply with the labeling requirements for "other covers". If a covers labeling does not say "safety", then it only meets non-safety cover standards. In order to legitimately bear a safety label, a cover must be able to pass the tests that satisfy the performance standards of ASTM F 1346-91.